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Charra [1.4K]
1 year ago
10

A particular battery claims to have a mean life of 400 hours with a standard deviation of 30 hours. Approximately what percent o

f the batteries will last more than 420 hours?
Mathematics
1 answer:
Svetach [21]1 year ago
3 0

Using the normal distribution, it is found that 25.14% of the batteries will last more than 420 hours.

<h3>Normal Probability Distribution</h3>

The z-score of a measure X of a normally distributed variable with mean \mu and standard deviation \sigma is given by:

Z = \frac{X - \mu}{\sigma}

  • The z-score measures how many standard deviations the measure is above or below the mean.
  • Looking at the z-score table, the p-value associated with this z-score is found, which is the percentile of X.

In this problem, we have that the mean and the standard deviation are given, respectively, by:

\mu = 400, \sigma = 30.

The proportion of the batteries will last more than 420 hours is <u>one subtracted by the p-value of Z when X = 420</u>, hence:

Z = \frac{X - \mu}{\sigma}

Z = \frac{420 - 400}{30}

Z = 0.67

Z = 0.67 has a p-value of 0.7486.

1 - 0.7486 = 0.2514.

0.2514 = 25.14% of the batteries will last more than 420 hours.

More can be learned about the normal distribution at brainly.com/question/24663213

#SPJ1

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