Both cats and dogs hunt small mammals. Biologists will randomly select 20 dogs and 20 cats living in northern England and attach video cameras to their collars. The biologists then observe how many small mammals each animal kills during a ten-day period. They plan to choose the dogs independently of the cats, and hope to come as close as possible to using simple random sampling, so they can use a test of two means with independent samples to determine whether cats kill more small mammals than dogs. Their hypotheses are H0:cats=dogs{"version":"1.1","math":"H_0:\mu _{\text{cats}}=\mu_{\text{dogs}}"} and Ha:cats> dogs{"version":"1.1","math":"H_a:\mu_{\text{cats}}> \ mu_{\text{dogs}}"}. Are the requirements for the hypothesis test of this question satisfied? Explain.

Question 35 options:

a) Yes. Independent simple random samples are all that is required.

b) Yes. They will have 40 subjects in all, which is more than 30.

c) No. They must have at least 30 cats and at least 30 dogs.

d) Not necessarily. Because they will only have 20 subjects in each sample, the data for each sample will have to be normal.