Question

the u.s. center for disease control reports that the mean life expectancy was 47.6 years for white people born in 1900 and 33.0 years for non - white people. suppose that you randomly survey death records for people born in 1900 in a certain county. of the 124 white people, the mean life span was 45.2 years with a standard deviation of 12.7 years. of the 82 non - white people, the mean life span was 34.1 years with a standard deviation of 15.6 years. conduct a hypothesis test to see if the mean life spans in the county were the same for white people and non - white people. which distribution (normal or students t) would you use for this hypothesis test? a. students t b. normal

Explanation:

When conducting a hypothesis test for the difference in means between two groups (White and non - White people in this case), if the population standard deviations are unknown (which is the case here as we are given sample standard deviations), we use the Student's t - distribution. The normal distribution is used when the population standard deviations are known.

Answer:

A. Student's t