Katie Sr Yr stats practice set 8 #1

A software developer wants to test whether their typing speed app improves users' typing speed.
12 users were measured before and after using the app for one week.
The table below shows each user's typing speed in words per minute (WPM):
Part 1: What type of test is appropriate for this scenario?

• 2-sample t-test

• Paired sample t-test

• 1-sample t-test

• 2-proportion z-test

Part 2: What are the correct null and alternative hypotheses?

• H0: μd = 0, H1: μd ≠ 0

• H0: μ1 = μ2, H1: μ1 < μ2

• H0: μd < 0, H1: μd = 0

• H0: μd = 0, H1: μd > 0

Part 3: What are the mean and standard deviation of the differences?

• dˉ = 4.0, sd = 1.91

• dˉ = 3.2, sd = 2.22

• dˉ = 4.5, sd = 1.65

• dˉ = 2.8, sd = 2.05

Part 4: What is the value of the test statistic?

• 6.88

• 5.11

• 7.25

• 4.73

Part 5: What is the P-value for this test?

• 0.004

• 0.031

• 0.0001

• < 0.0001

Part 6: What is the correct decision at α = 0.05?

• Reject H0

• Fail to reject H0

• Sample is too small

• Use a one-tailed test

Part 7: What is the correct conclusion based on this test?

• There is strong evidence that the app improves typing speed

• There is no significant difference in typing speed

• The results are inconclusive

• The app slows down typing speed

Part 8: What is the 95% confidence interval for the mean increase in typing speed?

• (3.1, 5.6)

• (2.786, 5.214)

• (3.4, 5.1)

• (2.2, 5.8)