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45 votes
45 votes
I need help with problem please

I need help with problem please-example-1
User Freedom Chuks
by
3.0k points

1 Answer

16 votes
16 votes

Answer: 705

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Step-by-step explanation:

mu = population mean = 1300

sigma = population standard deviation = 20

Compute the z score based on x = 1330

z = (x-mu)/sigma

z = (1330-1300)/20

z = 30/20

z = 1.5

Asking to compute P(X < 1330) is the same as P(Z < 1.5) in this specific context when mu = 1300 and sigma = 20.

Use a Z table or a calculator to find that P(Z < 1.5) is roughly 0.93319

About 93.319% of the 755 bulbs are expected to last less than 1330 hours.

0.93319*755 = 704.55845

That value rounds to 705

User YichenBman
by
3.4k points
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