Times spent studying by students in the week before final exams follow a normal distribution with standard deviation 9 hours. A random sample of 25 students was taken in order to estimate the mean study time for the population of all students. What is the probability that the sample mean is more than 3.2 hours above the population mean? A. 0.9625 B. 0.0375 C. 0.3594 D. 0.6406
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The standard error of the mean is the standard deviation divided by the square root of the sample size. In this case, the standard error is 9/sqrt(25) = 1.8 hours. Show more…
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