Question

USE ONLY EXCEL FOR SOLUTION!

The life of light bulbs is distributed normally. The standard deviation of the lifetime is 15 hours and the mean lifetime of a bulb is 590 hours. Using Excel, find the probability of a bulb lasting for at most 605 hours. Round your answer to four decimal places.

PLEASE USE ONLY EXCEL AND SHOW FORMULAS USED IN SOLUTION. THANK YOU!

Answer 1

Given: = 590 hours, = 15 hours

To find the probability, we need to find the Z scores first.

Z = (X - )/ [/Sqrt(n)].

Since n = 1, Z = (X - )/

P(At most 605) = P(X 605) = P(X < 605) since the z distribution is cumulative.

Z = (605 - 590) / 15 = 1

Using the excel formula NORMSDIST(1), the required probability = 0.8413

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The excel snap shot is below

X<a	n = 1
x	605
Mean	590
SD	15
x-mean	15.0
Z	1.000
p(Table)	0.84134