Question 5 of 8, Step 1 of 2 6/14
Correct
1
Steve believes that his wife's cell phone battery does not last as long as his cell phone battery.
On twelve different occasions, he measured the length of time his cell phone battery lasted and
calculated that the mean was 17.6 hours with a standard deviation of 5.8 hours. He measured the length
of time his wife's cell phone battery lasted on eight different occasions and calculated a mean of
20.5 hours with a standard deviation of 7.9 hours. Assume that the population variances are the
same. Let Population 1 be the battery life of Steve's cell phone and Population 2 be the battery life of his
wife's cell phone.
Step 1 of 2: Construct a 99 % confidence interval for the true difference in mean battery life between
Steve's cell phone and his wife's. Round the endpoints of the interval to one decimal place, if necessary.
nswer
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