Question

An electronic product takes an average of 9 hours to move through an assembly line. If the standard deviation of 0.9 hours, what is the probability that an item will take between 7.5 and 7.9 hours to move through the assembly line? Do not round until you get your your final answer, and then round to 3 decimal places.

Answer=   (Round your answer to 3 decimal places, and report a probability value between 0 and 1.)

Answer 1

Solution :

Given that,

mean = = 9 hours

standard deviation = = 0.9 hours

P ( 7.5 < x < 7.9 )

P ( 7.5 - 9 / 0.9 ) < ( x -  / ) < ( 7.9 - 9/ 0.9)

P ( - 1.5 / 0.9 < z < -1.1 / 0.9)

P (- 1.67 < z < -1.22 )

P (z < - 1.22 ) - p ( z < - 1.67 )

Using z table

= 0.1112 - 0.0475

= 0.0637

Probability = 0.064