Question

For a statistics class project, a college student randomly samples 75 men who exercise at a gym regularly and 68 women who exercise at a gym regularly. The college tudent believes that on average men spend more time at the gym each week. The college student records the number of minutes each person exercises in a given week. The college student conducts a hypothesis test at the 5% significance level.

Use the summary statistics to conduct a hypothesis test in StatCrunch. (Open an empty StatCrunch spreadsheet. Choose Stat, T Stats, two sample, with Summary. Adjust the alternative hypothesis as necessary Two Sample T-Test
Sample n Mean Std. Dev.
Men 75 65.7 13.9
Women 68 64.8 9.6
What conclusion can you draw from the output?
i. The data provide sufficient evidence to reject the null hypothesis and to conclude that the mean amount of exercise (minutes) is greater for men than for women at this gym.
ii. The data provide sufficient evidence to conclude that there is no difference in the mean number of minutes exercised per week for men and women.
iii. The data do not provide sufficient evidence to conclude that the mean number of minutes exercised per week is larger for men than for women at this gym

Answer 1

iii. The data do not provide sufficient evidence to conclude that the mean number of minutes exercised per week is larger for men than for women at this gym

Explanation:

1) The hypotheses are

H0: u1 ≤ u2 against the claim Ha: u1 > u2

The men spend less or equal time than the women at the gym each week

vs

the men spend greater time than the women at the gym each week

2) The test statistic is

t= (x1`- x2`) / √ s1²/n1+ s2²/n2

t= 65.7- 64.8/√(13.9)²/75 + (9.6)²/68

t= 0.9/√2.57613 +1.35529

t=0.4539

and the degrees of freedom is

3) υ = [s₁²/n1 + s₂²/n2]²/ (s₁²/n1 )²/ n1-1 + (s₂²/n2)²/n2-1

=[(13.9)²/75 + (9.6)²/68]²/ [(13.9)²/75 ]² /74 + [ (9.6)²/68]²/67

= 139

The degrees of freedom is always rounded in this calculation

4) The Critical region is [1.656, ∞]

5) t-score is outside of the critical region, so there is not enough evidence to reject H₀.

iii. The data do not provide sufficient evidence to conclude that the mean number of minutes exercised per week is larger for men than for women at this gym