Need help with the calculation and formula.

A survey of 144 retail stores revealed that the average price of a DVD was $375 with a standard error of $20.

If 90% and 95% confidence intervals were developed to estimate the true cost of the DVD, what similarities do they have?

a. Both require point estimates of the true cost.

b. Both use z statistics.

c. Both require standard errors of the true cost.

d. All are true.

A survey of an urban university (population of 25,450) showed that 750 of 1100 students sampled attended a home football game during the season. What inferences can be made about student attendance at football games?

Using the 99% level of confidence, what is the confidence interval?

a. [0.767, 0.814]

b. [0.0.6550, 0.7050]

c. [0.6659, 0.6941]

d. [0.0.6795, 0.6805]