The lifetimes of lightbulbs of a particular type are normally distributed with a mean of 400...

The lifetimes of lightbulbs of a particular type are normally distributed with a mean of 400 hours and a standard deviation of 10 hours. What percentage of the bulbs have lifetimes that lie within 2 standard deviations to either side of the mean? Use the Empirical Rule and write your answer as a percent rounded to 2 decimal places.

Solutions

Expert Solution

solution

using empirical rule

P( - 2< X < + 2) = 95%

P(400 - 2 * 10 < X <400 + 2 * 10) = 95%

P(380 < X < 420) = 95%

Answer = 95%

orchestra answered 2 years ago

Next > < Previous

Related Solutions

The lifetime of a certain brand of lightbulbs is normally distributed with the mean of 3800...

The lifetime of a certain brand of lightbulbs is normally distributed with the mean of 3800 hours and standard deviation of 250 hours. The probability that randomly selected lightbulb will have lifetime more than 3500 hours is ________ The percent of lightbulbs which have the lifetime between 3500 and 4200 hours is __________ What lifetime should the manufacturer advertise for these lightbulbs if he assumes that 10% of lightbulbs with the smallest lifetimes will burn out by that time? Advertised...

The lifetimes of light bulbs are normally distributed with a mean of 500 hours and a...

The lifetimes of light bulbs are normally distributed with a mean of 500 hours and a standard deviation of 25 hours. Find the probability that a randomly selected light bulb has a lifetime that is greater than 532 hours. SHOW FULL WORK!

The lifetimes of a certain electronic component are known to be normally distributed with a mean...

The lifetimes of a certain electronic component are known to be normally distributed with a mean of 1,400 hours and a standard deviation of 600 hours. For a random sample of 25 components the probability is 0.6915 that the sample mean lifetime is less than how many hours? A)1345 B)1460 C)1804 D)1790

Suppose that the lifetimes of light bulbs are approximately normally distributed, with a mean of 57...

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 60 hours? (b) What proportion of light bulbs will last 50 hours or less? (c) What proportion of light bulbs will last between 58 and 61 hours? (d) What is the probability that a randomly selected light bulb lasts less than 46 hours? (a)...

Suppose that the lifetimes of light bulbs are approximately normally distributed, with a mean of 56...

Suppose that the lifetimes of light bulbs are approximately normally distributed, with a mean of 56 hours and a standard deviation of 3.3 hours. With this information, answer the following questions. (a) What proportion of light bulbs will last more than 61hours? (b) What proportion of light bulbs will last 51 hours or less? (c) What proportion of light bulbs will last between 57 and 62 hours? (d) What is the probability that a randomly selected light bulb lasts less...

Suppose that the lifetimes of light bulbs are approximately normally distributed, with a mean of 57...

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 60 hours? (b) What proportion of light bulbs will last 50 hours or less? (c) What proportion of light bulbs will last between 57 and 61 hours? (d) What is the probability that a randomly selected light bulb lasts...

Suppose that the lifetimes of light bulbs are approximately normally distributed, with a mean of 57...

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 57 and 61 hours? (d) What is the probability that a randomly selected light bulb lasts...

Suppose that the lifetimes of light bulbs are approximately normally distributed, with a mean of 57...

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 61 hours? (b) What proportion of light bulbs will last 52 hours or less? (c) What proportion of light bulbs will last between 57 and 62 hours? (d) What is the probability that a randomly selected light bulb lasts...

Suppose that the lifetimes of light bulbs are approximately normally distributed, with a mean of 57...

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 61 hours? (b) What proportion of light bulbs will last 51 hours or less? (c) What proportion of light bulbs will last between 57 and 61 hours? (d) What is the probability that a randomly selected light bulb lasts...

Suppose that the lifetimes of light bulbs are approximately normally distributed, with a mean of 57...

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 60 hours? (b) What proportion of light bulbs will last 50 hours or less? (c) What proportion of light bulbs will last between 57 and 61 hours? (d) What is the probability that a randomly selected light bulb lasts...

Subjects