Solve the equation and check the solution . X-13.8=-20.4 the solution set is ?

Answer:

The sampling method described in this question appears to be sound

Step-by-step explanation:

It appears to be sound because the data are not biased in any way, since every member and set of members has an equal chance of being included in the sample selection. Also, random samples are usually fairly representative since they don't favor certain members.

Answer:

  neither

Step-by-step explanation:

The equation means that 600 is twelve times as many as 50 (not four times). Bill needs to rethink the meaning of "four" relative to the meaning of "12".

__

"650 more than 12" is an expression (12+650), not an equation. Sarah seems to be clueless.

__

Neither Bill nor Sarah have described the meaning of the equation.

11n - 6 is the algebraic expression for six less than the product of 11 and a number

Solution:

Given that,

Six less than the product of 11 and a number

Let "n" be the unknown number

Let us understand and break the given sentence

Six less than the product of 11 and a number

Which means,

six less than product of 11 and "n"

Which can be written as,

[tex]11n-6[/tex]

Thus the given sentence is translated into algebraic expression

The algebraic expression which represents 'six less than the product of 11 and a number' is 11n - 6, where n is the unknown number.

The question is asking for an algebraic expression representing 'six less than the product of 11 and a number'. To translate this to mathematical terms, first, the 'product of 11 and a number' indicates multiplication between 11 and the unknown number, which we represent with the variable n. The 'six less than' part indicates that we subtract 6 from this product.

So, the algebraic expression that represents 'six less than the product of 11 and a number' is 11n - 6.

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Answer:

20days

Step-by-step explanation:

The daily progress is 4ft - 3ft = 1ft

20ft/1ft = 20days

The snail will take 20 days to get out of the well.

To find out how long it will take the snail to get out of the well, we need to determine how many days it takes for the snail to climb a distance of 20 feet. Each day, the snail climbs 4 feet but slips back 3 feet at night. So, the net distance the snail covers each day is 4 - 3 = 1 foot.

Dividing the total distance of 20 feet by the net distance covered each day (1 foot), we find that it will take the snail 20 days to get out of the well.

Hence, the snail will take 20 days to get out of the well.

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Answer:

Lenght = 20m

Width = 30m

Step-by-step explanation:

Perimeter of a rectangular enclosure = 2(L+W)

Adding a length of the fence parallel to one side of the sudden to split the closure, the total is 2(L+W) + L = 120

Area of a rectangular closure = L*W

To find the dimension that would maximize the area solve for L and W.

2(L+W) + L = 120

2L + 2W + L = 120

3L + 2W = 120

2W = 120 - 3L

W = (120 - 3L)/2

Put the value of W into Area formula

A = L*W

A = L *(120 - 3L) /2

= L(60 - 1.5L)

= 60L - 1.5L^2

= -1.5L^2 + 60L

This is a quadratic equation. Compare to ax^2 + bx + c

L = -b/2a

a = -1.5, b= 60, c= 0

L = -60/2(-1.5)

= -60/-3

= 20m

Put L = 20 into the value of W

W = (120 - 3L) /2

W= (120 - 3*20) / 2

= (120 - 60)/2

= 60 / 2

= 30m

The dimensions are 20m by 30m

Anna bought 10 oranges

Explanation:

Let x denote the number of apples.

Let y denote the number of oranges.

The system of equations can be written as

[tex]x+y=25[/tex] and [tex]2x+3y=60[/tex]

Let us solve the equation by substitution method.

Thus, from [tex]x+y=25[/tex], the value of y can be determined such that [tex]y=25-x[/tex]

Using the y value [tex]y=25-x[/tex] in the equation [tex]2x+3y=60[/tex], we get,

[tex]2x+3(25-x)=60[/tex]

Multiplying 3 within the bracket,

[tex]2x+75-3x=60[/tex]

Adding the terms,

[tex]75-x=60[/tex]

Subtracting both sides by 75, we have,

[tex]x=15[/tex]

Thus, substituting [tex]x=15[/tex] in [tex]y=25-x[/tex], we get,

[tex]y=25-15\\y=10[/tex]

Thus, Anna get 10 Oranges.

Answer:

option A- The candidate each participant supports.

Step-by-step explanation: the question asks about the 'statistics in the experiment', meaning the major factor or say the most important data to be considered to achieve the desired aim/result of the experiment.

From the question, the aim/result of the Research poll was to get 'the PROPORTION of people supporting each presidential candidate in the fall election'. Note that to find 'PROPORTION',  you must first find the individual values and then compare them. That's what 'PROPORTION' is all about - comparing number of things or people.

So to achieve this, the most important data-'statistics' in this experiment is knowing the candidate each participant supports.

For example, if there are 5 presidential candidates: Mr A, B, C, D & E and after interviewing 2,010 adults, you find out that:

134 people supports Mr A;

268 people supports Mr B;

402 people supports Mr C;

536 people supports Mr D and

670 people supports Mr E.

Now because you know the candidate each participant supports, you can now derive the 'PROPORTION' of people supporting each candidate which is 134:268:402:536:670. NB: you have to always leave your answer in its lowest term, so the proprtion here is 1:2:3:4:5.

Answer:

The proportions of participants who support each presidential candidate.

Step-by-step explanation

Answer:

A'(8, -10)

Step-by-step explanation:

Firstly we have to know the distance from the point A to the line, the point is (8, 2) and the line is x = 5 .

the point has two components, at x and y

the component in y will give us the distance we have on the axis of the X thas is 2.

T he line is 5 units from the axis.

Now to know the distance we have to subtract

2 - 5 = -3

Here is the point with respect to the line x = 5

For the reflected over the line we just need to change the sign, now we got +3 .  To this we add the value of the line that is 5

3 + 5 = 8.

So the reflected point over the line x = 5 is (8, 8)

We do the same with the line x = -1.

(8, 8) and x = -1

..

8 - (-1) = 9

..

(-9) + (-1) = -10

(8, -10)

Answer:

The outcome of guessing the correct answers to a 50 question test is 12.5.

Step-by-step explanation:

Let us first consider one question.

Since it has 4 options so we can say that;

Total number of possible outcomes = 4

Since 1 answer is correct so we can say that;

Favorable outcome = 1

Now we can say that;

Probability for choosing correct answer can be calculated by Favorable outcome divided by Total number of possible outcomes.

framing in equation form we get;

[tex]P(Correct\ Answer) = \frac{1}{4}[/tex]

Now Given:

Total number of question = 50

So we can say that;

Total number of correct answer out of 50 is equal to Probability for choosing correct answer multiplied by Total number of question.

framing in equation form we get;

Guessing number of correct answer out of 50 = [tex]\frac14 \times 50 = 12.5[/tex]

Hence The outcome of guessing the correct answers to a 50 question test is 12.5.

You can use a binomial distribution model to simulate guessing the correct answers on a 50-question test with 4 answer choices per question.  The probability of getting at least 30 correct answers.

To simulate the outcome of guessing the correct answers to a 50 question test, you can use a binomial distribution model. A binomial distribution represents the probability of a certain number of successful outcomes in a fixed number of independent trials. In this case, the success would be guessing the correct answer.

Each question has 4 answer choices, so the probability of guessing the correct answer for each question is 1/4. The number of successful guesses in a 50-question test can follow a binomial distribution with parameters n = 50 (number of trials) and p = 1/4 (probability of success).

Using this model, you can calculate probabilities of various outcomes, such as the probability of getting exactly 20 correct answers by guessing

Hence, the probability of getting at least 30 correct answers.

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Answer:$4000 was invested into the account earning 6% interest.

$2000 was invested into the account earning 11% interest.

Step-by-step explanation:

Let x represent the amount invested into the account earning 6% interest.

Let y represent the amount invested into the account earning 11% interest.

Mike has $6000 to invest. He invested part of his total into an account earning 6% interest and the rest in an account earning 11% interest. This means that

x + y = 6000

The formula for simple interest is expressed as

I = PRT/100

Where

P represents the principal

R represents interest rate

T represents time in years

I = interest after t years

Considering the account earning 6% interest, the interest would be

I = (x × 6 × 1)/100 = 0.06x

Considering the account earning 11% interest, the interest would be

I = (x × 11 × 1)/100 = 0.11y

If at the end of the year, he earned $460.00 in interest, it means that

0.06x + 0.11y = 460 - - - - - - - - - - -1

Substituting x = 6000 - y into equation 1, it becomes

0.06(6000 - y) + 0.11y = 460

360 - 0.06y + 0.11y = 460

- 0.06y + 0.11y = 460 - 360

0.05y = 100

y = 100/0.05 = $2000

x = 6000 - y = 6000 - 2000

x = $4000

Answer: the cost of one cherry pie is $18 and the cost of one pumpkin pie is $20

Step-by-step explanation:

Let x represent the cost of one cherry pie.

Let y represent the cost of one pumpkin pie.

Lea sold 2 cherry pies and 4 pumpkin pies for a total of $116. This means that

2x + 4y = 116 - - - - - - - - - - - - - -1

Kali sold 7 cherry pies and 8 pumpkins pies for a total of $286. This means that

7x + 8y = 286 - - - - - - - - - - - - 2

Multiplying equation 1 by 7 and equation 2 by 2, it becomes

14x + 28y = 812

14x + 16y = 572

Subtracting, it becomes

12y = 240

y = 240/12 = 20

Substituting y = 20 into equation 1, it becomes

2x + 4 × 20 = 116

2x + 80 = 116

2x = 116 - 80 = 36

x = 36/2 = 18

Answer:

3. A matched-pairs t-test with H0 : μd = 0,  HA : μd ≠ 0

Step-by-step explanation:

An investigator wants to asses the difference in mean pulses rates between sitting and standing persons in population.

The matched paired t-test is appropriate choice because the observations in the data are paired. The observations in the data are the calculated pulse rates of 50 persons while sitting and standing. For each person. sitting and standing pulse rates are measured and this indicates the before and after effect is measured. The before and after effect is measured through matched paired t test.

Also,  an investigator wants to determine whether there is difference in mean pulse rates between sitting and standing in population. This indicates two tailed test. so, the hypotheses would be

Null hypotheses : μd = 0

Alternative hypotheses: μd ≠ 0.

Thus, situation indicates a matched-pairs t-test with H0 : μd = 0,  HA : μd ≠ 0.

The option that represents an appropriate test and hypotheses to determine if there is a difference in mean pulse rates between sitting and standing in the population is: Option C: A matched-pairs t-test with [tex]H_0 : \mu_d = 0\\H_A : \mu_d \neq 0[/tex]

The two-sample t-test is used to determine if two population means are equal.

When there has to be done comparison between means of two sets of paired data, then we use matched pair t test.

There are two hypotheses. First one is called null hypothesis and it is chosen such that it predicts nullity or no change in a thing. It is usually the hypothesis against which we do the test. The hypothesis which we put against null hypothesis is alternate hypothesis.

Null hypothesis is the one which researchers try to disprove.

For this case, we want to determine if there is a difference in mean pulse rates between sitting and standing in the population.

That is the reason why we will use matched pair t-test.

Where paired data is the pair of data obtained from each of those 50 people, the pair of data being sitting pulse rate and standing pulse rate.

Now, since we want to determine if there's any difference, so the null hypothesis will nullify the presence of any difference.

Thus, we get:

Null hypothesis = [tex]H_0: \mu_d = 0[/tex] (the difference between mean of sitting pulse rate and that of standing pulse rate is 0, therefore no difference).

This can be rewritten as: [tex]H_0: \mu_{\text{sitting}} = \mu_{\text{standing}}[/tex]

Alternate hypothesis = [tex]H_A: \mu_d \neq 0[/tex] or [tex]H_A: \mu_{\text{sitting}} \neq \mu_{\text{standing}}[/tex]

Thus, the option that represents an appropriate test and hypotheses to determine if there is a difference in mean pulse rates between sitting and standing in the population is: Option C: A matched-pairs t-test with [tex]H_0 : \mu_d = 0\\H_A : \mu_d \neq 0[/tex]

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Answer:

The (minimum) number of toothpicks required to make an acute angle scalene triangle is  3.

Step-by-step explanation:

The (minimum) number of toothpicks required to make an acute angle scalene triangle is  3.

All the angles in a an acute angled scalene triangle are less than 90°.

The above condition can be satisfied with a minimum of three toothpicks.

To create an acute-angled scalene triangle, three toothpicks are required.

To create an acute-angled scalene triangle, you would need 3 toothpicks. You can stick the toothpicks into a marshmallow or a gumdrop and position them in a way that forms a triangle with angles less than 90 degrees and with all sides of different lengths.

Answer:

2nd option

Step-by-step explanation:

given

BD = 4x

CE = 2x + 2

test each answer option by substituting the given values of x into each of the above equations and see if it is consistent with the given values for BD and CD in the answer options.

1st option, when x = 5,

BD = 4x = 4(5) = 20  (Consistent)

CE = 2x + 2 = 2(5) + 2 = 10 + 2 = 12 ( not consistent with CE=8)

2nd option, when x = 3/7,

BD = 4x = 4(3/7) = 12/7  (Consistent)

CE = 2x + 2 = 2(3/7) + 2 = 6/7 + 2 = 20/7 ( consistent with CE=20/7) (ANSWER)

3rd option, when x = 3,

BD = 4x = 4(3) = 12 (Consistent)

CE = 2x + 2 = 2(3) + 2 = 6 + 2 = 8 ( not consistent with CE=20)

Answer: The area of triangle is 25 sq. meters.

Step-by-step explanation:

Given : Area of a triangle = [tex]\dfrac{1}{2}bh[/tex] m, where b= base of triangle

h= height of triangle.

If a triangle has  5 meters long base and a height twice the length of the base,

that means b = 5 meters and h= 2(5) = 19=0 meters

Then the area of triangle becomes [tex]A=\dfrac{1}{2}(5)(10)=25 m^2[/tex]  [Put alll values in the given formula]

Hence, the area of triangle is 25 sq. meters.

Answer:

True

Step-by-step explanation:

A common denominator of the mixed numbers is 20. select True or false

Mr. Clements painted his barn for 3 3/5 hours in the morning.

[tex]3\frac{3}{5}=\frac{18}{5}[/tex]

He painted the barn for 5 3/4 hours in the afternoon.

[tex]5\frac{3}{4}=\frac{23}{4}[/tex]

Now we consider the denominator of both fractions 18/5 and 23/4

Least common denominator is 5  times 4 = 20

So its true that the common denominator of mixed numbers is 20

Answer:

Step-by-step explanation:

                    30/71 = 0.4225 = 42.25%

Answer:

Step-by-step explanation:

The value of the y-intercept is (0,7)

So the y intercept is 0,7

Answer:

Therefore the period of the sinusoidal wave = 3.14.

The amplitude of the function = 2.

Step-by-step explanation:

The period of a sinusiodal wave is given by the length of x axis which covers one full cycle of the wave, which one positive half-cycle and one negative half cycle.

From the graph we can see  that one of the cycles starts at -3.14 / 4 and ends at 3.14 [tex]\times[/tex] 3/4.

Therefore we can sutract the start point value from the end point value to get the period

Therefore period  = (3.14 [tex]\times[/tex] 3/4) - (-3.14 / 4) = (3.14 [tex]\times[/tex] 3/4) + (3.14 / 4) = 3.14

Therefore the period of the sinusoidal wave = 3.14.

The amplitude of the function = 2.

Answer: The amount she puts in a bag  = 0.912 pound.

Step-by-step explanation:

Given : Amount of red licorice purchased by Christy = 6.75 pounds

Amount of black licorice purchased by Christy  = 2.37 pounds

Total amount of licorice purchased by Christy =  6.75 + 2.37 pounds

= 9.12  pounds

Then, if she divides the total amount into 10 equal-sized bags  , the amount she put in a bag  = (Total amount of licorice purchased) ÷ 10

= 9.12  ÷ 10 = 0.912 pound

Hence, the amount she puts in a bag  = 0.912 pound.

Final answer:

To find how much licorice Christy needs to put into each of 10 bags, add the weights of red and black licorice and then divide by 10. She will need to put 0.912 pounds of licorice into each bag.

Explanation:

Christy purchased 6.75 pounds of red licorice and 2.37 pounds of black licorice. To find the total amount of licorice, we add the weight of the red and black licorice together:

Total weight of licorice = [tex]6.75 pounds + 2.37 pounds = 9.12 pounds.[/tex]

If she divides the total amount into 10 equal-sized bags, we divide the total weight by 10:

Weight per bag = [tex]9.12 pounds / 10 bags = 0.912 pounds per bag.[/tex]

Answer:

x = 144 children

y = 160 adults

Step-by-step explanation:

We have parameters already defined. Number of children that entered is x while number of admitted adults is y.

Since the total number of people admitted was 304, this means:

x + y = 304

Total fees for that day was 856

Mathematically:

1.5x + 4y = 856

From the first equation, we can say y = 304 - x

We then substitute this into the second equation:

1.5x + 4(304 - x) = 856

1.5x + 1216 - 4x = 856

1216-856 = 4x-1.5x

2.5x = 360

x = 360/2.5 = 144

Since y = 304 - 144

y = 160

The number of children admitted was 144 and the number of adult is 160

Answer:

At most 29 boxes can be safely loaded onto the pallet.

Step-by-step explanation:

Given:

Weight of each box = 55 pound

Weight pallet can support [tex]\leq[/tex] 1595 pounds.

We need to find the number of boxes .

Solution:

Let the number of boxes loaded safely onto the pallet be 'x'.

So we can say that;

Weight of each box Multiplied by number of boxes should be less than or equal to Weight pallet can support.

framing in equation form we get;

[tex]55x\leq 1595[/tex]

Dividing both side by 55 we get;

[tex]\frac{55x}{55}\leq \frac{1595}{55}\\\\x\leq 29[/tex]

Hence At most 29 boxes can be safely loaded onto the pallet.

Alan can safely load 29 boxes onto the pallet.

To determine how many boxes Alan can safely load onto the pallet, we need to divide the maximum weight the pallet can support by the weight of each box. The maximum weight the pallet can support is 1595 pounds, and each box weighs 55 pounds.

To find the number of boxes, we can divide the maximum weight by the weight of each box: 1595 ÷ 55 = 29.

Therefore, Alan can safely load 29 boxes onto the pallet.

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Answer:

The answer to your question is letter C

Step-by-step explanation:

From the graph, we get the center and the radius

- The center is the point shown in the graph and its coordinates are (2, -1).

- The length of the radius is 4 units, from the center we count horizontally the number of squares (4)

Substitution

                    (x - 2)² + (y + 1)² = 4²

or                 (x - 2)² + (y + 1)² = 16

Answer:

A or B

Step-by-step explanation:

Because of the negtive 1

Yo sup??

This question can be solved by applying the properties of similar triangles

the triangle with sides 5x and 20 is similar to the triangle with sides 45 and 35

The similarity property used here is called AAA ie angle angle angle property as all the three angles of the 2 triangles are equal.

therefore we can say

5x/45=20/36

x=5 units

Hope this helps

Answer:

a) 0.0125

b) 0.4579

Step-by-step explanation:

For this question use tree diagram method to solve the question or by simply listing down the probabilities as I have done in the attached picture. Firstly, we need to convert all percentages in to decimal and those decimals will represent probability of each event. For example if we consider probability of quality score A it can be found by diving 77 with 100:

77/100 = 0.77

Similarly all probabilities can be found by simply dividing percentages with 100.

Part (b) is a conditional probability question. Given that a circuit failed is the condition. So we need to use conditional probability method to solve it.

Final answer:

The probability of a circuit failing is 4.87%. If a circuit failed, there is a 45.77% chance that it received a quality score of C or D.

Explanation:

Calculating the Probability of Circuit Failure

To find the probability of a circuit failing, we multiply the probability of receiving each quality score by the probability of failure for that score, then add these together:

A score: 0.77 * 0.02 = 0.0154 (1.54%)

B score: 0.11 * 0.10 = 0.0110 (1.10%)

C score: 0.07 * 0.14 = 0.0098 (0.98%)

D score: 0.05 * 0.25 = 0.0125 (1.25%)

The total probability of failure is the sum of these values: 0.0154 + 0.0110 + 0.0098 + 0.0125 = 0.0487 or 4.87%.

Probability of a Failed Circuit Having a C or D Score

If a circuit failed, to find the probability that it had a quality score of C or D, we divide the sum of the probabilities of failure for C and D by the total probability of failure:

(Probability of C failure + Probability of D failure) / Total probability of failure
= (0.0098 + 0.0125) / 0.0487
= 0.0223 / 0.0487
= 0.4577 or 45.77%.

Answer:

Therefore,

[tex]x=9\\\\y=7[/tex]

Step-by-step explanation:

Given:

D,E,F are the midpoints of side AB, BC,and AC such that

AB = 4x - 18

BC = 2x - 4

DF = x

FE = y

To Find:

x = ?

y = ?

Solution:

Midpoint Theorem:

The Midpoint Theorem states that the segment joining two sides of a triangle at the midpoints of those sides is parallel to the third side and is half the length of the third side.  

E and F are Midpoint of Sides BC and AC, then

[tex]FE=\dfrac{1}{2}AB[/tex]        ......By Midpoint Theorem

Substituting the values we get

[tex]x=\dfrac{1}{2}(4x-18)=2x-9\\\\2x-x=9\\\\x=9[/tex]

Similarly,

D and Fare Midpoint of Sides AB and AC, then

[tex]DF=\dfrac{1}{2}BC[/tex]        ......By Midpoint Theorem

Substituting the values we get

[tex]y=\dfrac{1}{2}(2x-4)=x-2\\\\Substitute\ x=9\\\\y=9-2=7[/tex]

Therefore,

[tex]x=9\\\\y=7[/tex]

Answer:

-16y -10

Step-by-step explanation:

So basically, since there are no parentheses, we can use PEMDAS:

y - 9 * y - 8 * y - 10

y - 9y - 8y - 10

-8y -8y - 10

-16y -10

The answer is y^-7 I had this in my lesson

Answer:

175 means the city's population is 175 thousands in 2010.

Step-by-step explanation:

The model below gives the projection of the city's population , P, in thousands, with respect to time, t, in years, where 2010 corresponds to t=0.

The given equation is

[tex]P=175+\dfrac{11}{2}t[/tex]

We need to interpret 175 for the given model.

Substitute t=0 in the above equation.

[tex]P=175+\dfrac{11}{2}(0)[/tex]

[tex]P=175[/tex]

At t=0 the value of P is 175 it means the city's population is 175 thousands in 2010.

Answer: the value of the account after 10 years is $2606

Step-by-step explanation:

The formula for continuously compounded interest is

A = P x e (r x t)

Where

A represents the future value of the investment after t years.

P represents the present value or initial amount invested

r represents the interest rate

t represents the time in years for which the investment was made.

e is the mathematical constant approximated as 2.7183.

From the information given,

P = 1800

r = 3.7% = 3.7/100 = 0.037

t = 10 years

Therefore,

A = 1800 x 2.7183^(0.037 x 10)

A = 1800 x 2.7183^(0.37)

A = $2606 to the nearest dollar

To solve such problems we must know about Continuous Compound Interest.

[tex]A = Pe^{rt}[/tex]

where,

A is the principal amount after t number of years,

r is the rate at which the principal is been compounded, and P is the principal amount.

The value of Steve's account after 10 years will be $2,606.

As it is given in the problem, the account of Steve is compounding continuously.

Steve invests 1,800 in an account that earns 3.7% annual interest, compounded continuously.

Time period money invested for 10 years,

Substituting the values in the formula of Continuous Compound Interest,

[tex]A = Pe^{rt}[/tex]

[tex]\begin{aligned}A&=\$1800\times e^{0.037\times10}\\ &=\$2605.9\approx\$2606\\ \end{aligned}[/tex]

Hence, the value of Steve's account after 10 years will be $2,606.

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Answer: 6 minutes

Step-by-step explanation:

According to the Empirical rule ,

About 68% of the population lies within one standard deviation from the mean.

Given : Suppose the wait through immigration at JFK Airport in New York is thought to be bell-shaped and symmetrical with a mean of 22 minutes.

It is known that 68 percent of travelers will spend between 16 and 28 minutes waiting to pass through immigration.

i.e. Mean - standard deviation= 16

and Mean  + standard deviation =28

Since , Mean=22 , so we have

22+ standard deviation =28

⇒ standard deviation =28 -22 =6

Hence, the standard deviation for the wait time through immigration is 6 minutes .

The standard deviation for the wait time through immigration is 6 minutes.

To find the standard deviation, we can use the properties of the normal distribution, specifically the 68-95-99.7 rule, which states that approximately 68% of the data falls within one standard deviation of the mean, 95% within two standard deviations, and 99.7% within three standard deviations.

Given that 68% of travellers wait between 16 and 28 minutes, we can determine that these times represent one standard deviation from the mean. The mean wait time is 22 minutes. The range from 16 to 28 minutes is 12 minutes wide (28 - 16 = 12). Since this range represents one standard deviation on either side of the mean, we can divide this range by 2 to find the value of one standard deviation:

Standard deviation = (28 - 16) / 2 = 12 / 2 = 6 minutes.