A company installs 5000 light bulbs, each with an average life of 500 hours, standard deviation of 100 hours, and

Question

distribution approximated by a normal curve. Find the percentage of bulbs that can be expected to last the period of
time.
77) At least 500 hours

Answer 1

A normal distribution is symmetrical about the mean, which means that 50% of the cases are above the mean, and 50%, below.

So how many % of the lightbulbs will last at least 500 hours?