Question

PLEASE ANSWER ALL QUESTIONS!

1. Frank is testing if changing the shelf that candies are displayed on at a grocery store sales register changes the amount of sales. The old location averaged 27 sales per day at each register, with a standard deviation of 5.8. After 35 register-days (5 registers for 7 days), the average sales are 29.9. Frank wants to test the change at the 1% significance level.

What number(s) form the decision rule?

Select one:

a. -2.81 and 2.81

b. -2.33

c. -2.24

d. -2.58 and 2.58

e. 2.24

f. 2.33

2. Bernice gets into a discussion with her coworker about the bank account balance of a typical college student. Her coworker says that on average they have at least $100, while Bernice disagrees. They ask 34 students in a class to write down their bank account balance anonymously. They find the average student has a balance of $89. According to a bank manager, the standard deviation of balances for student accounts is typically $24. Use the 2.5% significance level.

Calculate the value of the test statistic.

Select one:

a. -2.08

b. -2.67

c. -3.19

d. -3.28

e. -3.53

Answer 1

1)

This is two tailed test, for α = 0.01
Critical value of z are -2.58 and 2.58.
Hence reject H0 if z < -2.58 or z > 2.58

Option d)

2)

Test statistic,
(xbar - mu)/(sigma/sqrt(n))
(89 - 100)/(24/sqrt(34))
= -2.67

Option b)