A sports writer wants to see if a football filled with helium travels farther, on average, than a football filled with air. 13 footballs were filled with helium to the recommend pressure and 12 footballs were filled with air to the recommended pressure. The mean yardage for the helium filled footballs was 229 yards with a standard deviation of 4 yards. The mean yardage for the air filled footballs was 2?6 yards with a standard deviation of 3 yards. Assume the populations are normal with equal variances. (a). Construct a 95% confidence interval for the mean difference in in yardage for the two types of footballs Lower bound ' ' (use 3 decimal places) Upper bound ' ' (use 3 decimal places) (b). What can you conclude about the sports writer's idea that helium footballs travel farther, on average? 0 The helium footballs travel farther on average than the other footballs O The helium footballs are no different than the other footballs, on average 0 The other footballs travel farther on average than the helium footballs