The physical plant at the main campus of a large state university receives daily requests to replace fluorescent light bulbs. The distribution of the number of daily requests is bell-shaped and has a mean of 63 and a standard deviation of 6. Using the 68-95-99.7 rule, what is the approximate percentage of light bulb replacement requests numbering between 63 and 75? _________ % (Round your answer to the nearest tenth of a percent)

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Answer:

the approximate percentage of light bulb replacement requests between 63 and 75 is 47.5%

Step-by-step explanation:

the 68-95-99.7 rule for a bell-shaped distribution states that

68% of the population is found between mean+ 1 standard deviation and the mean - 1 standard deviation

95% of the population is found between mean+ 2 standard deviations and the mean - 2 standard deviations

99.7% of the population is found between mean+ 3 standard deviations and the mean - 3 standard deviations

therefore since the

light bulbs = mean + x * standard deviation

75 = 63 + x* 6

x= (75-63)/6 = 2

therefore

mean + 2 * standard deviation = 75

mean - 2 standard deviations = 63- 2*6 = 51

and

95% of the light bulbs replacement requests are found between 51 and 75 daily requests

since the bell shaped distribution is symmetrical

95%/2 = 47.5 % is found between mean and mean + 2 * standard deviation

thus

47.5 % of the light bulbs replacements are found between 63 and mean + 2 * standard deviation = 75

47.5 % of the light bulbs replacements are found 51 and 63

Using the Empirical Rule, the approximate percentage of light bulb replacement requests numbering between 63 and 75 is of 47.5%.

According to the Empirical Rule, in a normal distribution:

  • 68% of the measures are within 1 standard deviation of the mean.
  • 95% are within 2.
  • 99.7% are within 3.

  • The normal distribution is symmetric, which means that 50% of the measures are above the mean and 50% are below.

In this problem:

  • Mean of 63, standard deviation of 6.
  • 75 = 63 + 2(6), which means that 75 is two standard deviations above the mean.
  • Of the 50% of the measures below the mean, 95% are between 63 and 75, so:

[tex]0.95(50) = 47.5[/tex]

The approximate percentage of light bulb replacement requests numbering between 63 and 75 is of 47.5%.

A similar problem is given at https://brainly.com/question/24244232