A study reported by the Michigan State campus newspaper stated that the average time MSU students spent studying last month was is 58.3 hours, with a standard deviation of 14 hours.If the study time distribution is normal, what percentage of students spent between 40 and 80 hours studying?
A).8443
B).7486
C).8051
D).7224
E)..8962

Question

Quizplus · Accepted Answer

To find the percentage of students who spent between 40 and 80 hours studying, we use the Z-score formula: Z = (X - μ) / σ, where X is the value, μ is the mean, and σ is the standard deviation. For 40 hours: Z = (40 - 58.3) / 14 = -1.307. For 80 hours: Z = (80 - 58.3) / 14 = 1.55. Looking these Z-scores up in a standard normal distribution table or using a calculator, we find the probabilities: P(-1.307 < Z < 1.55) ≈ 0.8443 or 84.43%.

A Study Reported by the Michigan State Campus Newspaper Stated