Question

Comparing Two Population Means - Example: Checkout Time The U-Scan facility was recently installed at the Byme Road Food- Town location. The store manager would like to know if the mearn checkout time using the standard checkout method is longer than using the U-Scan. She gathered the following sample information. The time is measured from when the customer enters the line until their bags are in the cart. Hence the time includes both waiting in line and checking out. Population Standard Deviation Customer Type Sample Mean Sample Size 50 100 5.50 minutes 0.40 minutes Standard 0.30 minutes 5.30 minutes U-Scan 11-4 Notes-Comments目:: -

Answer 1

As the population standard deviation is known, we will use the two sample z-test.

Null Hypothesis: mu_{​​​​​​​​​​1}​ <= mu2

Alternate Hypothesis: mu1 > mu2

X1 = 5.5, X2 = 5.30

The formula is:

We know the values, let's insert it into the formula:

Standard Error = 0.064

z = ((5.5-5.3) - 0)/0.064 = 3.125

P-value < 0.001

Hence, at 0.05 significance level, we can reject the null hypothesis.

We conclude that the mean checkout time for standard method is significantly longer than U-Scan.