The true length of boards cut at a mill with a listed length of 10 feet is normally distributed with a meanof 123 inches and a standard deviationof 1 inch. What proportion of the boards will be over 125 inches in length?
A z-score reveals how many standard deviations a value is above or below the mean. It is calculated as follows:
z-score = (value – mean)/(standard deviation)
Using the normal bell-shaped curve (standard normal distribution) one can look up what proportion of the …
This solution looks at the percent of normally distributed board lengths that will be above a certain length.