Suppose that the lifetimes of a certain kind of light bulb are normally distributed with a standard deviation of 110 hours. If exactly 99% of the bulbs die before 920 hours, find the mean lifetime of...

Extracted text: Suppose that the lifetimes of a certain kind of light bulb are normally distributed with a standard deviation of 110 hours. If exactly 99% of the bulbs die before 920 hours, find the mean lifetime of the bulbs. Carry your intermediate computations to at least four decimal places. Round your answer to at least one decimal place. hours ? Aa