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 18 adult male volunteers. These volunteers were randomly divided into two groups of nine 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 x1 = 300 yards with a standard deviation s1 = 8 yards. The mean yardage for Group 2 was x1 = 296 yards with a standard deviation s2 = 6 yards. Assume the two groups of kicks are independent. Let M1 and M2 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 air-filled football. Assuming two-sample t procedures are safe to use, test Ho : M1 = M2 versus Ha : M1 # M2. What do we conclude about the gas filling a football? O There is evidence of a difference in mean distance travelled between air-filled and helium-filled footballs. O There is no evidence of difference in mean distance travelled between air-filled and helium-filled footballs. O There is evidence of a difference in every distance travelled between air-filled and helium-filled footballs