
3.20. An important parameter in fiber-optic cable manufacturing is cable diameter D. Testing of the
manufactured product finds the diameter to be normally distributed with a mean diameter of 0.1 m with
a coefficient of variation of 0.02. A cable is considered unacceptable if its diameter is ±3% off the mean
value. What is the probability of a cable being unacceptable? Sketch the probability density function
and the unacceptable region.
Solution: From the information given:
σ = δµ = 0.02 ·0.1 = 0.002.
The diameter is normally ...