When Mason commutes to work, the amount of time it takes him to arrive is normally distributed with a mean of 38 minutes and a standard deviation of 3 minutes. Out of the 283 days that Mason commutes to work per year, how many times would his commute be longer than 41 minutes, to the nearest whole number?
Q. When Mason commutes to work, the amount of time it takes him to arrive is normally distributed with a mean of 38 minutes and a standard deviation of 3 minutes. Out of the 283 days that Mason commutes to work per year, how many times would his commute be longer than 41 minutes, to the nearest whole number?
Identify Information: Identify the given information and what we need to find.Mason's commute time is normally distributed with a mean μ of 38 minutes and a standard deviation σ of 3 minutes. We need to find out how many days out of 283 his commute time will be longer than 41 minutes.
Calculate z-score: Calculate the z-score for the commute time of 41 minutes.The z-score formula is: z=(X−μ)/σ, where X is the value we are comparing to the mean.For Mason's commute time, z=(41−38)/3=3/3=1.
Find Probability: Use the z-score to find the probability that Mason's commute time is longer than 41 minutes.We look up the z-score of 1 in the standard normal distribution table or use a calculator to find the area to the right of z=1. This area represents the probability that a given day's commute time will exceed 41 minutes.The area to the left of z=1 is approximately 0.8413, so the area to the right (which is what we want) is 1−0.8413=0.1587.
Calculate Number of Days: Calculate the number of days Mason's commute will be longer than 41 minutes.We multiply the probability by the total number of commuting days.Number of days = 0.1587×283≈44.9121.
Round Result: Round the result to the nearest whole number, as we cannot have a fraction of a day.Mason's commute will be longer than 41 minutes on approximately 45 days out of 283.
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