Question

1. Using the traditional hypothesis testing approach, calculate the critical value for testing the null hypothesis that the population mean is greater than or equal to 12, given a sample size of 49, a population standard deviation 6.06, and a significance level of 0.05. Round to two decimals.

K =  

2. The manager of a paint supply store wants to determine if the mean amount of paint contained in 1- gallon cans purchased from a nationally known manufacturer is actually less than 1-gallon. It is known that for this manufacturer the population standard deviation of the amount of paint is equal to 0.02 gallons. A random sample of 55.0 cans is selected, and the mean amount of paint per 1-gallon can is 1.01 gallons. Use a significance level of 0.05. Is (are) the critical region(s) for this test in the left tail, right tail, or both tail(s)?  Please answer with one of the following words: left, right, both.

Answer 1

1)

This is right tailed test, for α = 0.05
Critical value of z is 1.64

2)

This is left tailed test, for α = 0.05
Critical value of z is -1.64.

Hence reject H0 if z < -1.64