. The life of General Electric light bulbs are normally distributed with a mean

ID: 3359279 • Letter: #

Question

. The life of General Electric light bulbs are normally distributed with a mean of 200 hours and a standard deviation 20 hours.

Due to the different methods, I rounded out to 2 decimal places. Select the best possible answer.

a. What is the probability that a randomly selected light bulb will last more that 210 hours? [ Select ] ["0.54", "0.14", "0.31", "0.81"]

b. What is the probability that a random sample of 10 light bulbs has a mean life greater than 210 hours?

a) 0.18

b) 0.33

c)0.006

d)0.27

= 200 = 20

a. x > 210

z > (x - ) /

=> z > (210 - 200) / 20

=> z > 0.5

P(z > 0.5) = 0.3085 = 0.31.

b. x' > 210

n = 10

z > (x - ) / * n

=> z > (210 - 200) / 20 * 10

=> z > 1.5811

P(z > 1.5811)

= 0.0569

= 0.06

Note: None of the answers is correct. It looks like c) should have been 0.06.

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.