wanted to determine how much volume

a 15-inch balloon could hold before bursting. He

randomly assigned 80 balloons to either be filled with a

measured volume of air or a measured volume of water.

The mean volume of air that was pumped into 40

balloons prior to bursting was 1.02 cubic feet with a

standard deviation of 0.18 cubic feet. The mean volume

of water that was pumped into the other 40 balloons prior

to bursting was 0.95 cubic feet with a standard deviation

of 0.28 cubic feet.

Do these data provide convincing evidence that the

true mean volume prior to bursting is different for

air-filled versus water-filled balloons?

Check the conditions for this two-sample t-test.

We have independent random samples of 40 air-

filled and 40 water-filled balloons.

We have data from 2 groups in a randomized

experiment.

40 <10% of all air-filled balloons and 10 <10% of

all water-filled balloons.

The 10% condition does not apply.

The Normal/Large Sample condition is not met.

The Normal/Large Sample condition is met

because both group sizes are large (at least 30).