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Chapter 6: Q. 52 (page 358)

Sulé’s job is just a few bus stops away from his house. While it can be faster to take the bus to work than to walk, the travel time is more variable due to traffic. The commute time B if Sulé takes the bus to work on a randomly selected day has mean 12 minutes and standard deviation 4 minutes. The commute time W if Sulé walks to work on a randomly selected day has mean 16 minutes and standard deviation 1 minute. Calculate and interpret the mean of the difference D=B−W in the time it would take Sulé to get to work on a randomly selected day?

Short Answer

Expert verified

The resultant difference of mean isμ=−4

Step by step solution

01

Given information

μB=12σB=4μW=16σW=1

B=Bus commuting time

W=when conversing on the way to work

02

Calculations

μ=μB−μW=12−16=−4

Because there are two means for two different random variables μB=12 and μW=16, the mean of the two random variables will be the difference of their means, resulting in a commute time by bus that is on average 4 minutes less than a commute by walking.

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