A research firm wants to compute an interval estimate with 95% confidence for the mean time to complete an employment test. Assuming a population standard deviation of 4.7 hours, what is the required sample size if the error should be less than a half hour?

(Notes: Use a whole number, for example: 235)

b. What is the upper bound of the interval? (correct answer to 4 decimal places!)

A market research dept. in a fastfood company collected information on the number of meals eaten outside the home per week by young married couples. 

A survey of 60 couples showed the sample mean number of meals eaten outside the home was 4.12 meals per week with standard deviation 0.25 meal per week. 

Construct a 99% confidence interval for the population mean.

a. What is the lower bound of the interval? (correct answer to 4 decimal places!)

b) The upper limit is

A survey of an university showed that 367 of 1,500 students sampled supported to change the online learning into hybrid learning. 

Construct a 97% confidence interval for the proportion of all students who support the hybrid learning.

a) The lower limit is

Choose true or false in response to the following statement.

PT. XYZ produces AA batteries used in remote-controlled toy cars. The mean life of these batteries follows the normal probability distribution with a mean of 35.0 hours and a standard deviation of 5.5 hours. As a part of its quality assurance program, PT. XYZ tests samples of 20 batteries.

What is the probability that the sample mean of useful life is between 34.5 and 36.0 hours? (round answer to 4 decimal places)

In Jakarta, the mean age of men when they marry for the first time follows the normal distribution with a mean of 29 years. The standard deviation of the distribution is 3.5 years. For a random sample of 20 men, what is the likelihood that the age when they were first married is greater than 30 years? (round answer to 4 decimal places)

Select True/False following statements: