Question

Pleaseee help

Lisa has collected data to find that the number of pages per book on a book shelf has a normal distribution. What is the probability that a randomly selected book has fewer than 170 pages if the mean (k) is 195 pages and the standard deviation (o) is 25 pages? Use the empirical rule. Enter your answer as a percent rounded to two decimal places if necessary.

Answer 1

Approximately 16%

Explanation:

To solve this problem using the empirical rule, we need to first standardize the value of 170 pages using the mean and standard deviation provided:

z = (x - k) / o

where x is the value we want to find the probability for (170 pages), k is the mean (195 pages), and o is the standard deviation (25 pages).

So,

z = (170 - 195) / 25 = -1

Now, we can use the empirical rule, which states that for a normal distribution:

- About 68% of the data falls within 1 standard deviation of the mean

- About 95% of the data falls within 2 standard deviations of the mean

- About 99.7% of the data falls within 3 standard deviations of the mean

Since we know that the distribution is normal, and we want to find the probability that a randomly selected book has fewer than 170 pages (which is one standard deviation below the mean), we can use the empirical rule to estimate this probability as follows:

- From the empirical rule, we know that about 68% of the data falls within 1 standard deviation of the mean.

- Since the value of 170 pages is one standard deviation below the mean, we can estimate that the probability of randomly selecting a book with fewer than 170 pages is approximately 16% (which is half of the remaining 32% outside of one standard deviation below the mean).

Therefore, the probability that a randomly selected book has fewer than 170 pages is approximately 16%.