Question

An electronic product takes an average of 8 hours to move through an assembly line. If the standard deviation of 0.7 hours, what is the probability that an item will take between 7.3 and 8.3 hours to move through the assembly line? Do not round until you get your your final answer. Answer= (Round your answer to 4 decimal places, and report a probability value between 0 and 1.)

Answer 1

Let a random variable X denote the No. of hours an electronic product takes to move through an assembly line. Assuming that X is approximately normlayy distributed:

Defining the Standard Normal variable:

  

To find:

..................(Rounding the upper Z value (8.3-8)/ 0.7 )

From Standard Normal table:

= 0.66640 - 0.15866

= 0.50774

To get a more exact figure (without rounding the upper Z value (8.3-8)/ 0.7 ), we may use the excel function: