Westonci.ca is the best place to get answers to your questions, provided by a community of experienced and knowledgeable experts. Experience the ease of finding quick and accurate answers to your questions from professionals on our platform. Experience the convenience of finding accurate answers to your questions from knowledgeable experts on our platform.

The life of light bulbs is distributed normally. The standard deviation of the lifetime is 15 hours and the mean lifetime of a bulb is 520 hours. Find the probability of a bulb lasting for at most 528 hours. Round your answer to four decimal places.

Sagot :

Answer:

0.7031 = 70.31% probability of a bulb lasting for at most 528 hours.

Step-by-step explanation:

Normal Probability Distribution

Problems of normal distributions can be solved using the z-score formula.

In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the z-score of a measure X is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

The standard deviation of the lifetime is 15 hours and the mean lifetime of a bulb is 520 hours.

This means that [tex]\sigma = 15, \mu = 520[/tex]

Find the probability of a bulb lasting for at most 528 hours.

This is the p-value of Z when X = 528. So

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]Z = \frac{528 - 520}{15}[/tex]

[tex]Z = 0.533[/tex]

[tex]Z = 0.533[/tex] has a p-value of 0.7031

0.7031 = 70.31% probability of a bulb lasting for at most 528 hours.