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).