Construct confidence interval

1. Construct a 90% confidence interval for the population mean of the weights of elephants.

The standard deviation of the weights of elephants is known to be approximately 16 pounds.

We wish to construct a 90% confidence interval for the mean weight of newborn elephant

calves. Seventy newborn elephants are weighed. The sample mean is 250 pounds. The sample standard deviation is 12 pounds. Round your answer to two decimal places.

Answer:

2. Construct a 85% confidence interval for the population mean weight of the heads of lettuce.

A sample of 28 heads of lettuce was selected. Assume that the population distribution of

head weight is normal. The weight of each head of lettuce was then recorded. The mean

weight was 2.4 pounds with a standard deviation of 0.15 pounds. The population standard

deviation is known to be 0.24 pounds. Round your answer to four decimal places.

Answer:

Answer the Question

3. A sample of 28 heads of lettuce was selected. Assume that the population distribution of

head weight is normal. The weight of each head of lettuce was then recorded. The mean

weight was 2.4 pounds with a standard deviation of 0.15 pounds. The population standard

deviation is known to be 0.24 pounds. What would happen if 24 heads of lettuce were

sampled instead of 28, and the confidence level remained the same?

Answer:

Define the random variable X in words.

4. The mean age for all Foothill College students for a recent Fall term was 33.2. The

population standard deviation has been pretty consistent at 15. Suppose that twenty-five

Winter students were randomly selected. The mean age for the sample was 30.4. We are

interested in the true mean age for Winter Foothill College students.

Answer:

Find error bound for the problem below.

5. The mean age for all Foothill College students for a recent Fall term was 30.8. The

population standard deviation has been pretty consistent at 14.6. Suppose that forty-one

Winter students were randomly selected. The mean age for the sample was 29.7. We are

interested in the true mean age for Winter Foothill College students. Find EBM for 95%

confidence interval. Stated to two decimal places.

Answer:

Answer the question

6. The mean age for all Foothill College students for a recent Fall term was 30.8. The

population standard deviation has been pretty consistent at 14.6. Suppose that 41 Winter

students were randomly selected. The mean age for the sample was 29.7. We are

interested in the true mean age for Winter Foothill College students.

Using the same mean, standard deviation and level of confidence, suppose that n were 36

instead of 41. Would the error bound become larger or smaller? Explain why.

Answer:

Which distribution should you use for the following problems?

7. A survey of the mean number of cents off that coupons give was conducted by randomly surveying one coupon per page from the coupon sections of recent San Jose Mercury News. The following data were collected: 20 cents; 75 cents; 50 cents; 65 cents; 30 cents; 55 cents; 40 cents; 40 cents; 30 cents; 55 cents; $1.50; 40 cents; 65 cents; 40 cents. Assume the underlying distribution is approximately normal. Why?

Answer:

Construct confidence interval.

8. Construct a 90% confidence interval for the population mean worth of coupons.

A survey of the mean number of cents off that coupons give was conducted by randomly surveying one coupon per page from the coupon sections of a recent San Jose Mercury News. The following data were collected: 20 cents; 75 cents; 50 cents; 65 cents; 30 cents; 55 cents; 40 cents; 40 cents; 30 cents; 55 cents; $1.50; 40 cents; 65 cents; 40 cents. Assume the underlying distribution is approximately normal. State the confidence interval in dollar values rounded to three decimal places.

Answer:

Answer the question.

9. A survey of the mean number of cents off that coupons give was conducted by randomly surveying one coupon per page from the coupon sections of a recent San Jose Mercury News. The following data were collected: 20 cents; 75 cents; 50 cents; 65 cents; 30 cents; 55 cents; 40 cents; 40 cents; 30 cents; 55 cents; $1.50; 40 cents; 65 cents; 40 cents. Assume the underlying distribution is approximately normal. The 90% confidence interval contains population mean.

If many random samples were taken of size 14, what percent of the confidence intervals constructed from the samples should contain the population mean worth of coupons? Explain why.

Answer:

10. You are testing that the mean speed of your cable Internet connection is more than forty Megabits per second. What is the random variable? Describe in words.

Answer:

State the Type I and Type II errors in complete sentences.

11. A group of doctors is deciding whether or not to perform an operation. Suppose the null hypothesis, H0, is the surgical procedure will go well.

Answer:

Calculate the margin of error.

12. A group of doctors is deciding whether or not to perform an operation. Suppose the null hypothesis, H0, is: the surgical procedure will go well. Which is the error with the greater consequence?

Answer:

Compute the probability.

13. The power of a test is 0.886. What is the probability of a Type II error?

Answer: