MATLAB: An Introduction with Applications
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ISBN: 9781119256830
Author: Amos Gilat
Publisher: John Wiley & Sons Inc
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Transcribed Image Text:A sports writer wants to see if a football filled with helium travels farther, on average, than a football filled
with air. 10 footballs were filled with helium to the recommend pressure and 11 footballs were filled with
air to the recommended pressure. The mean yardage for the helium filled footballs was 231 yards with a
standard deviation of 5 yards. The mean yardage for the air filled footballs was 234 yards with a standard
deviation of 2 yards.
Construct a 98% confidence interval for the mean difference in yardage for the two types of footballs.
Assume the populations are normal with equal variances. Round your answers to three decimal places, and
use four decimal places for any interim calculations.
Hint: Identify the type of t-procedure, and complete the confidence interval accordingly.
We are 98% confident that the interval -7.141 X 1.141 x) contains the true mean difference
12 in yardage between the two types of footballs.
What can you conclude about the sports writer's idea that helium footballs travel farther, on average?
O The helium footballs travel farther on average than the other footballs.
The other footballs travel farther on average than the helium footballs.
O The helium footballs are no different than the other footballs, on average.
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