Question

Do people walk faster in an airport when they are departing​(getting on a​ plane) or after they have arrived​ (getting off a​plane)? An interested passenger watched a random sample of people departing and a random sample of people arriving and measured the walking speed​ (in feet per​ minute) of each. A hypothesis test is to be performed to determine if the mean walking speed is different between departing and arriving passengers at an airport. One of the conditions that must be satisfied for conclusions from a​two-sample t-test to be valid is that the samples are representative of their respective populations. Is the condition satisfied in this​ problem?

A. The samples will be representative of their respective populations only if both sample sizes are at least​ 50% of the population sizes.
B. Because the people observed in the study were randomly​selected, the passengers in each sample should be representative of all departing and arriving passengers at the airport where the samples were taken.
C. The departing and arriving passengers in the samples will be representative of all departing and arriving passengers at the airport where the samples were taken as long as walking speeds in both populations follow a normal distribution.
D. As long as each sample size is at least​ 30, the samples will be representative of their respective populations.

Answer 1

B

Explanation:

The sample must be represenatative of whole population. Random selection ensures this.