A sports writer wished to see if a football filled with helium travels farther, on average, than a football filled with air. To test this, the writer used 20 adult male volunteers. These volunteers were randomly divided into two groups of 10 subjects each. Group 1 kicked a football filled with helium to the recommended pressure. Group 2 kicked a football filled with air to the recommended pressure. The mean yardage for group 1 was = 32 yards, with a standard deviation s₁ = 9 yards. The mean yardage for group 2 was = 27 yards, with a standard deviation s₂ = 6 yards. Assume the two groups of kicks are independent. Let ₁ and ₂ represent the mean yardage we would observe for the entire population represented by the volunteers if all members of this population kicked, respectively, a helium and an air-filled football. Assume that two-sample t procedures are safe to use. Suppose the researcher had wished to test the hypotheses

H0: 1 = 2, Ha: 1 > 2.

The numerical value of the two-sample t statistic is

1.46.

0.36.

4.08.

2.57.