A researcher wants to prove that there is a difference in the average life spans between men and
women in Japan. Let mu1 = average life span of Japanese women and mu2 = average life span of
Japanese men. A random sample of 10 women showed an average lifespan of 83 years, with a
sample standard deviation of 7 years. A random sample of 10 men showed an average lifespan of
77 years, with a sample standard deviation of 6.4 years. Assume that life spans are normally
distributed and that the population variances are equal. The test statistics for this problem is 2.00.
If alpha= .05 and the null hypothesis is mu1 - mu2 = 0, what is your conclusion after the difference
of means hypothesis test?
There is a statistically significant difference in average life spans for men and women.
O The difference is not statistically significant: there is not enough evidence to conclude that the average life
spans are different.
The average life span of women is 6 years longer than the average life span of men.
None of the above.