Question

An electronic product takes an average of 9 hours to move through an assembly line. If the standard deviation is 0.7 hours, what is the probability that an item will take between 8.7 and 9.2 hours to move through the assembly line?

Answer 1

8.7 is 0.42σ below the mean
9.2 is 0.28σ above the mean
So what does your Z table say?