The advertising department of a nationally circulated magazine wishes to estimate the mean age of.its subscribers to within 0.5 year with 90% confidence. if they estimate that the standard deviation of the ages of their subscribers is 5 years, find the required sample size.a. 165
b. 17
c. 271
d. 45 1 points first question previous question question 14 of 30 next question last question

Answers

Answer 1

Answer: The correct answer is C) 271.

We first find the z-score associated with this confidence interval:
Convert 90% to a decimal: 90/100 = 0.9
Subtract from 1: 1 - 0.9 = 0.1
Divide by 2: 0.1/2 = 0.05
Subtract from 1: 1 - 0.05 = 0.95

Looking this value up in a z-table, we see that this number is the same distance from 1.64 and 1.65; therefore we will use 1.645.

Now we will use the following formula to calculate the sample size required:
$n=((z_(\alpha/2)*\sigma)/(E))^2\n\n=((1.645*5)/(0.5))^2=270.6\approx 271$

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If $A^3=I$ , then $A^3=AA^2=I$ which means $A$ and $A^2$ must be inverses of one another, so $(A^2)^(-1)=A$ and $A^(-1)=A^2$ , so $A$ must be invertible.

The United Van Lines moving company has a truck filled for deliveries to five different sites. If the order of the deliveries is randomly selected, what is the probability that it is the shortest route?

Answers

Answer:

0.8333%

Step-by-step explanation:

Assuming that there is only one possible shortest route, the probability that a randomly selected route is given by one divided by the permutation of the order of five different sites:

$P=(1)/((5!)/((5-5)!))=(1)/(5*4*3*2*1)\n P=0.008333=0.8333\%$

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Suppose that a medical test has a 92% chance of detecting a disease if the person has it (i.e., 92% sensi- tivity) and a 94% chance of correctly indicating that the disease is absent if the person really does not have the disease (i.e., 94% specificity). Suppose 10% of the popu- lation has the disease. (a) What is the probability that a randomly chosen per- son will test positive

Answers

Answer:

14.6% probability that a randomly chosen person will test positive

Step-by-step explanation:

We have these following probabilities:

10% probability that a randomly selected person has the disease.

If a person has the disease, 92% probability of testing positive.

100-10 = 90% probability that a person does not have the disease.

If a person does not have the disease, 100-94 = 6% probability of testing positive.

What is the probability that a randomly chosen person will test positive

92% of 10% or 6% of 90%.

Then

p = 0.92*0.1 + 0.06*0.9 = 0.146

14.6% probability that a randomly chosen person will test positive

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Answers

Answer:

D. 113.04

Step-by-step explanation:

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Answers

Answer:

A.2 B.4 C.3 D.4 E.6

Step-by-step explanation:

1/2 ÷ 3/4 = 1/2 x 4/3 (flip 3/4 and keep 1/2)

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Daryl invested $2,200 for 3 years. He received interest of $264. What was the interest rate?

Answers

Answer:

Step-by-step explanation:

264 interest/3 years=88 interest/year

principal x interest rate =interest/year

2200 x interest rate =88

interest rate =88/2200

interest rate =.04 or 4%

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