Question

NEED HELP ASAP laboratory tests show that the lives of light bulbs are normally distributed with a mean of 750 hours and a standard deviation of 75 hours. find the probability that a randomly selected light bulb will last between 900 and 975 hours.

Answer 1

Answer:

0.0214

Step-by-step explanation:

We can get these answer by finding the z-scores at first

Mathematically;

z-score = x-mean/sd

For 900;

z-score = 900-750/75 = 150/75 = 2

For 975

z-score = (975-750)/75 = 3

So the probability we want to calculate is;

P(2<x<3)

This can be calculated using the standard normal distribution table

From the standard score table;

P(2<x<3) = 0.0214