Suppose that the lifetimes of light bulbs are approximately normally​ distributed, with a mean of 57 hours and a standard deviation of 3.5 hours. With this​ information, answer the following questions.   ​(a) What proportion of light bulbs will last more than 62 ​hours? ​(b) What proportion of light bulbs will last 52 hours or​ less? ​(c) What proportion of light bulbs will last between 59 and 62 ​hours? ​(d) What is the probability that a randomly selected light bulb lasts less than 45 ​hours?

Features Features Normal distribution is characterized by two parameters, mean (µ) and standard deviation (σ). When graphed, the mean represents the center of the bell curve and the graph is perfectly symmetric about the center. The mean, median, and mode are all equal for a normal distribution. The standard deviation measures the data's spread from the center. The higher the standard deviation, the more the data is spread out and the flatter the bell curve looks. Variance is another commonly used measure of the spread of the distribution and is equal to the square of the standard deviation.