Recall that researchers found that the time x (in hours) until the first critical part failure is exponentially distributed with 10 and 10 Now consider a random sample of n 50 NASCAR races and let x represent the sample mean time until the first critical part failure a Find E() and Var() b Although...

Recall that researchers found that the time x (in hours) until the first critical-part failure is exponentially

Question:

Recall that researchers found that the time x (in hours) until the first critical-part failure is exponentially distributed with µ = .10 and σ = .10. Now consider a random sample of n = 50 NASCAR races and let x represent the sample mean time until the first critical-part failure.
a. Find E() and Var().
b. Although x has an exponential the sampling of x is approximately normal. Why?
c. Find the probability that the sample mean time until the first critical-part failure exceeds .13 hour.
For Information: Refer to the Sport Journal (Winter 2007) analysis of critical-part failures at NASCAR races, Exercise 4.144.
Distribution
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