Houghton Mifflin Harcourt Algebra 1, 2015
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Houghton Mifflin Harcourt Algebra 1, 2015 View details
4. Normal Distributions
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Exercise 15 Page 342

Find the difference between the mean height and the given height in terms of standard deviations.

95 %

Practice makes perfect

We have been told that the heights of adult males are normally distributed with a mean of 72 inches and a standard deviation of 2 inches. We will find the percentage of men who are between 68 and 76inches tall. 68inches ≤ x≤ 76inches First, let's find the difference between 68inches and the mean. 72inches- 68inches=4Then, we will divide the difference by the standard deviation. 4 inches/2inches=2 Therefore, 68inches is 2 standard deviations below the mean. Next, let's find the difference between 76 inches and the mean. 76 inches- 72 inches= 4 inches Again, we will divide the difference by the standard deviation. 4 inches/2 inches=2 Thus, 76 inches is 2 standard deviations above the mean. To find the probability, we will shade the data that is no more than 2 standard deviations below the mean and no more than 2 standard deviations above the mean.

Finally, we can find the probability that a randomly chosen man is between 68 and 76 inches tall by adding the percentage of data in the shaded regions.

p=13.5 %+34 %+34 %+13.5 %
p=95 %

The probability that a randomly chosen man is between 68 and 76 inches tall is 95 %.