A GE lightbulb is supposed to last for 1,200 hours. In fact, light bulbs of this type last only 1,185 hours with a standard devi

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A GE lightbulb is supposed to last for 1,200 hours. In fact, light bulbs of this type last only 1,185 hours with a standard devi

ation of 70 hours. What is the probability that a sample of 100 lightbulbs will have an average life of at least 1,200 hours? Mathematics

Mathematics

1 answer:

dybincka [34] · Answer 1 · 2022-03-20T19:51:33+03:00

This can be solved using the formula for t test which is = x - mu over standard deviation divided by the square root of the number of samples. In this case, it is 1185 - 1200 over 70 divided by square root of 100 which give us a value of 2.14 which is equal to .9839 in area. Only rarely, just over one time in a hundred tries of 100 light bulbs, would the average life exceed 1200 hours.