Assume the resting heart rates for a sample of individuals are normally distribu

Question

Assume the resting heart rates for a sample of individuals are normally distributed with a mean of 75 and a standard deviation of 5. Use the 68-95-99.7 rule to find the following quantities.

a. The relative frequency of rates less than 85 using the 68-95-99.7 rule is _____. (Round to three decimal places as needed.)

b. The relative frequency of rates greater than 80 using the 68-95-99.7 rule is _____. (Round to three decimal places as needed.)

c. The relative frequency of rates between 65 and 75 using the 68-95-99.7 rule is _____. (Round to three decimal places as needed.)

Explanation / Answer

a)

For x = 85, it is 2 standard deviations above the mean.

Hence, 100 - (100 - 95)/2 = 97.5% is below it. [ANSWER]

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b)

For x = 80, it is 1 standard deviation above the mean.

Hence, (100 - 68)/2 = 16% is above it. [ANSWER]

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c)

65 is 2 standard deviations below the mean.

hence, 95/2 = 47.5% is between 65 and 75. [ANSWER, 47.5%]

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