An instructor gives an exam with fourteen questions. Students are allowed to choose any ten to answer. a. How many different choices of ten questions are there?

b. Suppose six questions require proof and eight do not.

(i) How many groups of ten questions contain four that require proof and six that do not?

(ii) How many groups of ten questions contain at least one that requires proof?

(iii) How many groups of ten questions contain at most three that require proof?

c. Suppose the exam instructions specify that at most one of questions 1 and 2 may be included among the ten. How many different choices of ten questions are there? d. Suppose the exam instructions specify that either both questions 1 and 2 are to be included among the ten or neither is to be included. How many different choices of ten questions are there?





Answers

Answer 1

There are 1001 different choices of 10 questions.

d. Since the student can choose any 10 questions out of the 14, the number of different choices of 10 questions is given by the combination formula, which is C(14,10). Using the formula for combinations, we have:

C(14,10) = 14! / (10!(14-10)!)

= 14! / (10!4!)

= (14*13*12*11) / (4*3*2*1) = 1001

Therefore, there are 1001 different choices of 10 questions.

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Related Questions

The marginal cost function of producing q mountain bikes is Upper C Superscript prime Baseline left-parenthesis q right-parenthesis equals StartFraction 600 Over 0.3 q plus 5 EndFraction. (a) If the fixed cost in producing the bicycles is dollar-sign 2300, find the total cost to produce 30 bicycles. Enter an answer to two decimal places. dollar-sign 4359.23 (b) If the bikes are sold for dollar-sign 220 each, what is the profit (or loss) on the first 30 bicycles? Enter an answer to two decimal places. dollar-sign 2240.77 (c) Find the marginal profit on the 31st bicycle. Enter an answer to two decimal places. dollar-sign

Answers

MArginal cost is the adjustment in all out cost that emerges when the amount created changes by one unit.(In another word subordinate of cost wrt unit) 
So we coordinate to get Cost work 
∫30 600/0.3q+5 (dq) 0
we get 9798.66 from joining. 
We add that to settle cost 2059.23+2200=4259.24 
So 4259.24 is the cost. 
Income from offering the bicycle is 205*30=6150 
and Profit=Revenue-Cost 
6150 - 4259.24=1890.76 
Presently Marginal Profit 
MArginal benefit is the term used to allude to the contrast between the minor cost the peripheral income for delivering one extra unit of creation. 
Marginal Profit=Marginal Revenue-Marginal Cost 
Marginal Cost=600/0.3q+5. 
We should connect to 31 to get 41.958 
Revenue= 205q 

Marginal rev=205 
Marginal Profit = 205-41.958=163.042

Last year, Melissa opened an investment account with

$6200

. At the end of the year, the amount in the account had decreased by 

29.5%

. How much is this decrease in dollars? How much money was in her account at the end of last year?

Answers

Melissas account had decreased by $1,829. The money in Melissa's account was now $4,371.

In the week before and the week after a​ holiday, there were 10,000 total​ deaths, and 4958 of them occurred in the week before the holiday. a. Construct a 95​% confidence interval estimate of the proportion of deaths in the week before the holiday to the total deaths in the week before and the week after the holiday. b. Based on the​ result, does there appear to be any indication that people can temporarily postpone their death to survive the​ holiday?

Answers

Thank you for posting your question here at brainly. I hope the answer will help you. Feel free to ask more questions here.
Below is the solution:

p-hat = 5445 / 11000 = 0.495

For a 95% confidence interval, use z = 1.96

The confidence interval is then:

p-hat - z(√(p-hat)(1 - p-hat) / n) < p < p-hat + z(√(p-hat)(1 - p-hat) / n)

0.495 - (1.96)(√(0.495)(1 - 0.495) / 11000) < p < 0.495 + (1.96)(√(0.495)(1 - 0.495) / 11000)

0.486 < p < 0.504

Sherry had an ending balance of $125.36, outstanding deposits of $153.53, and outstanding checks of $100.19. What was her checkbook balance?

Answers

$253.42 maybe the answer. But, I think it was the right answer :)


Answer: $178.70

Step-by-step explanation: $125.36 + $153.53 = $278.89

$278.89 - $100.19 = $178.70


is 65 milliometers bigger or 5 centimeters bigger?

Answers

65 millimeters 
5 centimeters=50 milimeters
Yes i see that 65millimeter is bigger than 5centimeter because, let me prove that 65millimeter is bigger than 5centimeter,now start,65/1000 is equal to 0.065 the 1000 is milli mean 1000.and centimeter mean 100 so 5/100 is equal to 0.05 so 65 is millimeter bigger than 5 centimeter.

if (7^2)^x=1, what is the value of x?

Answers

We have our equation and can see that we can simplify a little, giving us 49^x=1. We also know that anything to the power of zero equals one, so x=0.

if N/8+6=58, then N equals?

Answers

N equals 416

Hope this helps!

N/8+6-6=58-6
N/8*8=52*8
N=416
The answer is N equals 416

rewrite as a logarithmic equation.
7^0=1

Answers

Convert the exponential equation to a logarithmic equation using the logarithm base ( 7 ) 7 of the right side ( 1 ) 1 equals the exponent ( 0 ) 0 . log 7 ( 1 ) = 0


A certain component is critical to the operation of an electrical system and must be replaced immediately upon failure. If the mean lifetime of this type of component is 100 hours and its standard deviation is 30 hours, how many of the components must be in stock so that the probability that the system is in continual operation for the next 2000 hours is at least .95?

Answers

Final answer:

To calculate the stock required for continuous operation for 2000 hours with components having a mean lifetime of 100 hours and a standard deviation of 30 hours, use the Z-score for a 0.95 probability and solve for the number of components. This involves applying the normal distribution.

Explanation:Calculating Stock Quantity for Component Replacement

The given problem requires calculating the number of electrical components that must be in stock to ensure continuous operation of an electrical system for 2000 hours. We are to assume that the components have a mean lifetime of 100 hours and a standard deviation of 30 hours. The aim is to keep the probability of the system running without interruption at 0.95 or higher.

Firstly, determine the number of lifetimes within the 2000-hour period:

2000 hours / 100 hours = 20 lifetimes.

Next, apply the concept of the normal distribution to find the z-score that corresponds to the 0.95 cumulative probability. Looking at z-tables or using statistical software, we find that the z-score for 0.95 is approximately 1.645.

Now, calculate the stock required using this z-score. The formula for the z-score in this context is:

Z = (X - mean) / (standard deviation / sqrt(n))

where X is the total hours (2000), mean is 100, standard deviation is 30, and n is the number of components.

Rearrange the formula to solve for n:

1.645 = (2000 - (100n)) / (30 / sqrt(n))

Solve for n to get the required number of components in stock.

This is a complex statistics problem that requires knowledge of z-scores and the normal distribution to solve. Given that this requires more complex calculations and potentially the use of calculators or software, a more detailed step-by-step calculation may go beyond the scope of this platform.

Final answer:

To ensure the probability of continuous operation for the next 2000 hours is at least 0.95, at least one component must be in stock.

Explanation:

To calculate the number of components that must be in stock to ensure the probability of continuous operation for the next 2000 hours is at least 0.95, we need to use the concept of the normal distribution. Given that the mean lifetime of the component is 100 hours and the standard deviation is 30 hours, we can calculate the Z-score for 2000 hours.

Z-score = (X - mean) / standard deviation = (2000 - 100) / 30 = 63.33

Using a Z-table or calculator, we can find that the probability of the component lasting for 2000 hours or more is approximately 1. With a probability of 1, we can say that the system is guaranteed to be in continual operation for the next 2000 hours. Therefore, at least one component must be in stock.

An ordinary (fair) die is a cube with the numbers 

1

 through 

6

 on the sides (represented by painted spots). Imagine that such a die is rolled twice in succession and that the face values of the two rolls are added together. This sum is recorded as the outcome of a single trial of a random experiment.

Compute the probability of each of the following events:

Event 

A

: The sum is greater than 

9

.
Event 

B

: The sum is divisible by 

5

 or 

6

 (or both).

Answers


There are a few ways to look at this. If you wanted to look at all the events, you could draw a 6 x 6 grid and label the left side from 1 to 6 and the bottom from 1 to 6. The intersection of a row and a column would be a possible sum. You can check to see if the event you want to occur occurs on a cell by cell basis. Like if you wanted to see how many possibilities are there to get a sum of 12. We know there is only one way, that is to roll a 6 and a 6. Then you would shade the top right corner cell of the grid and check the other ones (for more complicated events). Then the probability is just the number of shaded cells divided by the total number of cells.

But, since you can probably just count the events, how many ways are there to roll any two numbers, if the order matters, there are 36 possibilities (6 x 6 grid). You could roll 4 then 6, 6 then 4, 5 then 5, 5 then 6, 6 then 5, and 6 then 6. There are 6 possibilities with a sum more than 9 and 36 total, so the probability of that one event is 6/36 or 1/6. Try out the last one ;)





Final answer:

The probability of rolling a sum greater than 9 (Event A) on two fair dice is 1/6, and the probability of rolling a sum divisible by 5 or 6 (Event B) is 1/3.

Explanation:

To compute the probability of Event A, where the sum is greater than 9, we first identify the possible combinations that yield a sum greater than 9: (4,6), (5,5), (5,6), (6,4), (6,5), and (6,6). Since there are 6 possible outcomes and 36 total possible outcomes when rolling two dice (6 for the first die × 6 for the second die), the probability is 6/36 or 1/6.

For Event B, we look for sums divisible by 5 or 6. These sums are 5, 6, 10, 12, 15, 18, and 20. The combinations yielding these sums are (1,4), (2,3), (2,6), (3,2), (3,6), (4,1), (4,6), (5,1), (5,5), (6,2), (6,3), (6,6). By counting these results, we have 12 outcomes that meet the Event B criteria out of 36, so the probability is 12/36 or 1/3.

The probability of Event A, the sum being greater than 9, is 1/6, and the probability of Event B, the sum being divisible by 5 or 6, is 1/3.

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June Elloy makes a 22 percent down payment on a home in Rockford, Illinois. What is the purchase price of the home assuming her down payment is $35,200?


Answers

0.22x = 35200
x=160000
the price is $160000

Answer:

Total purchase price of of the home is $160000

Step-by-step explanation:

We know that

Percent of down payment June Elloy makes = 22 %

Down payment is = $35200

Let x be the total purchase price.

Therefore,

22 % of x = 35200

( 22 / 100 ) times x = 35200

0.22 times x =35200

x = 35200 / 0.22

  = 160000

Thus, total purchase price of of the home is $160000

21/24 reduced fraction

Answers

21/24
Divide 21 by 3. You get 7.
Divide 24 by 3. You get 8.
7/8 is your answer
Find the Greatest Common Factor (GCF) of 21,24

Method 1: By Listing FactorsList out all factors of each number, and find the first common one.

Factors of 21

 : 1, 3, 7, 21

Factors of 24

 : 1, 2, 3, 4, 6, 8, 12, 24

Therefore, the GCF is 3. 

Divide both the numerator and the denominator by the GCF 

21÷3​​
                            = 7/8    = Solution 
24÷3 


Solve 2x + 6 - 10x = 30

Answers

2x+6-10x=30
2x - 10x = 24
  x=-3

There were 3,905 more hits on the school’s website in January than February. February had 9,854 hits.
How many hits did the school’s website have during both months?

Answers

Add 9,854 and 3,905. That would be how many hits there were in January. Then you add 9,854 to that number and the answer is 23,613
If February had 9,854 hits, then you would just add 3,905 to that number to get 13,759, and just add that to 9,854 to get the answer of 23,613.

The ratio of the sum of two numbers to the difference of the two numbers is 9. The product of the two numbers is 80. Find the numbers.

Answers

There are two equations here:

(a+b)/(a-b) = 9 and ab=80

the first one simplifies to 8a = 10b or a = (4/5)b.

You can plug this last part in for 'a' in the second equation:

(4/5)b*b = (4/5)b^2 = 80 which means b^2 = 64 or b = +8 or -8.

I guess the question asks for the positive solution, so then you will find that a = 10 if you plug the value of b in for one of the original equations. Then your final answer would be a = 10 and b = 8. But, there is another solution, I believe, that is a = -10 and b = -8, since ab would still equal 80 and (a+b)/(a-b) would be -18/-2 which still equals 9. Notice that either a and b are both positive or both negative, because this is the only time that the product of both numbers would be also positive.

trying to simplify 3√128

Answers

43√2 you could also write in decimal form.

What conclusion is appropriate if a chi-square test produces a chi-square statistic near zero?

Answers

expected values are close to observed values, tend to favor the null hypothesis; existence of relationship is not supported, or like, departure from expectation is not supported.

Final answer:

If a chi-square test produces a chi-square statistic near zero, it implies that there is minimal deviation between the observed and expected values, suggesting independence or a good fit. However, interpretation should consider the specific test and hypotheses.

Explanation:

If a chi-square test produces a chi-square statistic near zero, it implies that there is minimal deviation between the observed and expected values. This suggests that the variables being tested are independent of each other or that the data fits the assumed distribution very well.

For example, in a chi-square test of independence, if the chi-square statistic is close to zero, it indicates that there is no significant relationship between the two factors being tested.

However, it is important to interpret the results in the context of the specific test being conducted, considering the null and alternative hypotheses as well as the significance level.

write
23/25 as a percent

Answers

3 / 25 = x / 100 

23/25 = 0.92 = 92/100 

x = 92%
Convert the fraction to a decimal, then multiply by 100.
= 92%

A machine starts dumping sand at the rate of 20 m3/min, forming a pile in the shape of a cone. The height of the pile is always twice the length of the base diameter. After 5 minutes, how fast is the area of the base increasing?

Answers

When after 5 min the height is 11.516, after 5 min the height is increasing at .7678m/min, after 5 min the base radius is increasing at .19196 m/min, so I already workd out the volume formula v=1/3pir^2h

Final answer:

The area of the base is increasing at a rate of 200π m²/min after 5 minutes.

Explanation:

To find how fast the area of the base is increasing, we first need to calculate the rate at which the height and radius of the cone are changing. Given that the height of the pile is always twice the length of the base diameter, we can write the equation h = 2r, where h is the height and r is the radius of the cone. Differentiating both sides with respect to time, we get dh/dt = 2dr/dt. Since the height is changing at a constant rate of 20 m³/min, dh/dt = 20 m³/min. Using this information, we can find the rate at which the radius is changing, dr/dt. Since the base diameter is equal to 2r, the base radius changes at a rate of dr/dt = 10 m/min. Now, we can find the rate of change of the area A of the base using the formula A = πr². Differentiating both sides with respect to time, we get dA/dt = 2πr(dr/dt). Plugging in the values, we have dA/dt = 2π(10)(10) = 200π m²/min. Therefore, the area of the base is increasing at a rate of 200π m²/min after 5 minutes.

Karen works for 85 hours throughout a two-week period. She earns $1,891.25 throughout this period. how much does she earn for 8 hours to work?

Answers

85 Hours throughout a two-week period She earns 1,891.25$

The simplest way to do this is 1,891.25$/85Hours=E

E= 22.25$ per hour, Now that we know that we can multiply 22.25$ by 8, To get 8 hours instead of 1

Equation: 22.25*8 = A

A/Answer= 178$ For 8 hours of Work

Round 0.125 to the nearest tenth.

Answers

It would be .13. 
We round the 2 up since five is to the right either way it makes no different to the tenths place.
Answer: 0.13

After rounding off the given number 0.125 to the nearest tenth it becomes 0.1.

We know that,

When you round a number to a certain digit, you have to check the value of the digit before the place you want to round off to.

1. If the number you are rounding is followed by 5, 6, 7, 8, or 9, round the number up.

2. If the number you are rounding is followed by 0, 1, 2, 3, or 4, round the number down.

The given number is:

0.125

To round off this digit nearest tenth,

See the number at the hundredth place, which is 2.

And 2 < 5  

Therefore,

0.125 is rounded down to 0.1

So after rounding 0.125 number becomes 0.1.

Hence,

The rounded-off number nearest tenth is 0.1.

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x+3y-2z=10, -x-2y+z=-7, 3x+9y-5z=28

Answers

hmm
what you do is try to eliminate 1 variable in 2 equaions first
we can elminate x's in first and 2nd equation

add first and 2nd equation
x+3y-2z=10
-x-2y+z=-7 +
0x+y-z=3
y-z=3


multiply 2nd equation by 3 and add to last one
-3x-6y+3z=-21
3x+9y-5z=28 +
0x+3y-2z=7

3y-2z=7

we now have
y-z=3
3y-2z=7
multiply first equation by -2 and add to 2nd

-2y+2z=-6
3y-2z=7 +
y+0z=1
y=1

now we can sub back
y-z=3
1-z=3
minus 1
-z=2
times -1
z=-2

sub baack into any equation
x+3(1)-2(-2)=10
x+3+4=10
x+7=10
minus 7
x=3

x=3
y=1
z=-2
(3,1,-2)

  
[tex]\displaystyle \\ ~~~~x+3y-2z=10 ~~~~~(E_1)\\ -x-2y+z=-7 ~~~~~(E_2)\\ ~~3x+9y-5z=28~~~~~(E_3) \\ \text{- - - - - } \\ E_1 + E_2 ~~\Longrightarrow~~y - z = 3 \\ \\ -3 \times E_1 + E3 ~~\Longrightarrow~~ z = -2 \\ \\ \Longrightarrow\Longrightarrow\Longrightarrow \\ \\ y-z=3\\ z = \boxed{-2}\\ \text{- - - - - }\\ y-(-2)=3\\ y+2=3\\ y =3-2=\boxed{1}\\ \text{- - - - - }\\ x+3y-2z=10\\ x+3\cdot 1-2\cdot (-2)=10\\ x+3+4=10\\ x+7=10\\ x= 10 - 7 = \boxed{3}[/tex]



what is 0.79 as a fraction in simplest form

Answers

79/100 is the simplest form
0.79 = 79/100. I don't believe you can simplify past this point because 79 is a prime number

Two accounts each begin with a deposit of ​$5000. Both accounts have rates of 5.7​%, but one account compounds interest once a year while the other account compounds interest continuously. Show the amount in each account and the interest earned after one​ year, five​ years, ten​ years, and 20 years.

Answers

The answer for 1 year is 1,000

I need help with a math problem.

Answers

11.2+4+3.4+7.3+(11.2-3.4)=
11.2+4+3.4+7.3+7.8=
33.7

your perimeter is 33.7 m
All you have to do is just add the sides, in order to find the perimeter.

4m + 3.4m + 7.3m + 11.2m = 25.9m

A box contains
4

plain pencils and
4

pens. A second box contains
5

color pencils and
7

crayons. One item from each box is chosen at random. What is the probability that a pen from the first box and a crayon from the second box are selected?

Write your answer as a fraction in simplest form.



Answers

1. You have 3 chances in 12 of picking a pencil ===> 3/12 = 1/4

2 You have 5 chances in 8 of picking a colored pencil ===> 5/8

3. The probability of doing both is the product of the two ===> 1/4 * 5/8 = 5/32

Find the future value and interest earned if ​$8904.56 is invested for 8 years at 6​% compounded ​(a) semiannually and ​(b) continuously.

Answers

continuously. which is B

The Future value is $ 15162.80 and Interest is $6258.26

What is Future Value?

The worth of a current asset at some point in the future based on an estimated rate of growth is known as future value (FV). For investors and financial planners, the future value is crucial because they use it to predict how much an investment made now will be worth in the future.

Investors can make wise investment choices based on their projected demands by knowing the future worth. However, external economic forces that depreciate an asset's value, such inflation, might have a negative impact on the asset's future worth.

Given:

P = ​$8904.56

R= 6%

T= 9

n= 2

Now, Future Value = P [tex](1 + r/n)^ {(nt)}\\[/tex]

FV= 8904.56 [tex](1 + 0.06/2)^ {(2)(9)}\\[/tex]

FV = 8904. 56 [tex]( 1+ 0.03)^{18[/tex]

FV= 8904.56[tex](1.03)^{18}[/tex]

FV = $15162.80

And Interest = FV - P

Interest = 15162. 80 - 8906.4

Interest = $6258.26

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how do you write 84,052 in word form

Answers

It would be, Eighty-four thousand, and fifty two

You can ride your bike around your block twice and the whole neighborhood once in 15 minutes. You can ride your bike around your block twice and the whole neighborhood 5 times in 55 minutes. How long does it take you to ride around the neighborhood?

Answers

It takes 10 minutes to ride around your neighborhood. We already know that going around the neighborhood once and your block twice is 15 minutes, so you can get rid of the two blocks and one neighborhood. Then subtract 15 minutes from 55, which is 40. So now we know that it takes 40 minutes to go around the neighborhood 4 times. Devide, and you get that one lap around the neighborhood is 10 minutes. It's kinda hard to explain in words, but maybe the picture will help.

To determine the time it takes to ride around the neighborhood, equations are set up from the given scenarios and solved algebraically, resulting in 10 minutes for one neighborhood lap.

To solve the problem, we need to set up equations based on the information provided. Let's let N represent the time it takes to ride around the neighborhood once and B represent the time it takes to ride around the block twice. The first scenario gives us:

B + N = 15 minutes

In the second scenario, the only difference is the number of neighborhood laps, so:

B + 5N = 55 minutes

Subtracting the first equation from the second gives us:

4N = 40 minutes

Dividing both sides by 4, we find:

N = 10 minutes

Therefore, it takes 10 minutes to ride around the neighborhood once.

When 50% of a number is added to the number, the result is 225. What is the number?

Answers

Final answer:

The unknown number in the problem is 150. This was determined by creating an equation based on the information given, simplifying it, and solving for the unknown variable 'n'.

Explanation:

This is a math problem that involves working with percentages and algebraic equations. Let the unknown number we're trying to find be 'n'. The problem says that 50% of the number, which is 0.5*n, is added to the number (n), resulting in 225. This situation can be represented with the equation: n + 0.5*n = 225.

Combining like terms on the left side of the equation, we get 1.5*n = 225. To isolate 'n', divide both sides of the equation by 1.5. So, n = 225 / 1.5, which gives us the number 150. Therefore, the unknown number is 150.

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