1. General Electric manufactures a decorative Crystal Clear 60-watt light bulb that it advertises will last 1500 hours. Suppose the lifetimes of the light bulbs are approximately normally distributed with a mean of 1553 hours and a standard deviation of 40 hours.

Using the Standard normal table, determine the following probabilities (SHOW ALL WORK);round answers to 4 decimal places.

i. (2) What proportion/probability will the light bulbs last less than the advertised time (1500 hours)?

ii. (2) What proportion/probability will the light bulbs last more than 1600 hours?

iii. (3)What proportion/probability will the light bulbs last between 1525 and 1625 hours?

iv.(3) If the company gives a money-back guarantee that their light bulb lasts a certain amount of time, and it does not want to give more than 5% of customers their money back. What is the smallest lifetime they should advertise for their bulb to the nears 10 hours?