The claim of the manufacturer of cell phone batteries is that the median life of a battery is more than 40 hours.Suppose a random sample of 75 batteries finds that 32 have a life of more than 40 hours.Does the evidence support their claim? Which is the corresponding test statistic result?
A)-1.39
B)1.96
C)-1.96
D)1.39
E)1.55

Question

Quizplus · Accepted Answer

The test statistic for a one-sample proportion test is calculated using the formula for a z-test. Here, the sample proportion is 32/75, and the hypothesized proportion is 0.5 (since the median implies 50%). The calculated z-value is approximately -1.39, which does not support the claim that the median life is more than 40 hours.

The Claim of the Manufacturer of Cell Phone Batteries Is