Question

According to a human modeling​ project, the distribution of foot lengths of women is approximately Normal with a mean of 23.3 centimeters and a standard deviation of 1.2 centimeters. In the United​ States, a​ woman's shoe size of 6 fits feet that are 22.4 centimeters long. What percentage of women in the United States will wear a size 6 or​ smaller?

Answer 1

Answer:

22.66% of women in the United States will wear a size 6 or​ smaller

Step-by-step explanation:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$, the zscore of a measure X is given by:

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

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this problem, we have that:

$\mu = 23.3, \sigma = 1.2$

In the United​ States, a​ woman's shoe size of 6 fits feet that are 22.4 centimeters long. What percentage of women in the United States will wear a size 6 or​ smaller?

This is the pvalue of Z when X = 22.4. So

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

$Z = \frac{22.4 - 23.3}{1.2}$

$Z = -0.75$

$Z = -0.75$ has a pvalue of 0.2266

22.66% of women in the United States will wear a size 6 or​ smaller