Performing Hypothesis Tests: Means: Videos & Practice Problems

Consider the following data representing the number of annual deaths from heat waves in the United States over $20$ consecutive years: $54,49,47,53,50,36,42,46,41,33,38,31,29,35,21,30,32,44,17,22$. Assume these data are a random sample of recent annual heat wave deaths. At the $0.01$ significance level, test the claim that the mean number of annual heat wave deaths is less than the mean of $80.2$ deaths from the $1960$s. If the mean is now lower, mention one factor that might explain the reduction.