#1 Find the critical value t_c for the confidence level c=.90 and sample size n=6.

#2 Construct the indicated confidence interval for the population mean using the t-distribution. Assume the population is normally distributed.

c=0.90, x=14.6, s=0.54, n=14

#3 Using the standard normal distribution or the t-distribution to construct a 95% confidence interval for the population mean.

In a random sample of 17 mortgage institutions, the mean interest rate was 3.57% and the standard deviation was 0.47%. Assume the interest rates are normally distributed.

(a) Which distribution should be used to construct the confidence interval?

(b) Select the correct choice

1. The 95% confidence interval is

or

2. Neither distribution can be used to construct the confidence interval

(c) Interpret the results.

#4 Let p be the population proportion for the following condition. Find the point estimates for p and q.

In a survey of 1935 adults from country A, 475 said that they were not confident that the food they eat in country A is safe.

The point estimate for p, p, is

The point estimate for q, q, is

(Round to three decimal places.)

#5 Us the given confidence interval to find the margin of error and the sample proportion.

(0.610, 0.640)

#6 In a survey of 2310 adults, 744 say they believe in UFOs.

Construct a 95% confidence interval for the population of adults who believe in UFOs. Interpret the results.

(a) A 95% confidence interval for the population proportion is

(b) Interpret the results.

#7 Find the critical values X²L and X²R for the given confidence level c and sample size n.

c=0.9, n=26

X²L=?

X²R=?

#8 Find the critical values X²L and X²R for the given confidence level c and sample size n.

c=0.99, n=22

X²L=?

X²R=?

#9 Use technology to construct the confidence intervals for the population variance and the population standard deviation. Assume the sample is taken from a normally distributed population.

c-0.90, s=37, n=17

(a) The confidence interval for the population variance is

(b) The confidence interval for the population standard deviation is