Grinstead-Snell-Probability · Problem 6.3.11

Sums of Random Variables

Mathematics · expected-value-variance-continuous

Problem

The Pilsdorff Beer Company runs a fleet of trucks along the 100 mile road from Hangtown to Dry Gulch. The trucks are old, and are apt to break down at any point along the road with equal probability. Where should the company locate a garage so as to minimize the expected distance from a typical breakdown to the garage? In other words, if XX is a random variable giving the location of the breakdown, measured, say, from Hangtown, and bb gives the location of the garage, what choice of bb minimizes E(∣X−b∣)E(|X - b|)? Now suppose XX is not distributed uniformly over [0,100][0, 100], but instead has density function fX(x)=2x/10,000f_X(x) = 2x/10{,}000. Then what choice of bb minimizes E(∣X−b∣)E(|X - b|)?

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