Kevlar epoxy is a material used on the NASA space shuttles. Strands of this epoxy were tested at the 90% breaking strength. The following data represent time to failure (in hours) for a random sample of 50 epoxy strands (Reference: R. E. Barlow, University of California, Berkeley). Let x be a random variable representing time to failure (in hours) at 90% breaking strength.

(a) Find the range.
(b) Use a calculator to verify that ˆ‘x = 62.11 and ˆ‘x2 ‰ˆ 164.23.
(c) Use the results of part (b) to compute the sample mean, variance, and standard deviation for the time to failure.
(d) Interpretation Use the results of part (c) to compute the coefficient of variation. What does this number say about time to failure? Why does a small CV indicate more consistent data, whereas a larger CV indicates less consistent data? Explain.

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0.54 1.80 1.52 2.05 1.03 1.18 0.80 1.33 29 1.11 3.34 1.54 0.08 0.12 0.60 0.72 0.92 .05 1.43 3.03 1.81 2.17 0.63 0.56 0.03 0.09 0.18 0.34 5 1.45 1.52 0.19 1.55 0.02 0.07 0.65 0.40 0.24 5 1.45 1.60 1.80 4.69 0.08 7.89 1.58 1.64 0.03 0.23 0.72