Question

the average number of chocolate chips in a particular brand of chocolate chip chewy cookie is 19. the standard deviation is 2.6.assuming that the number of chocolate chips per cookie is normally distributed, what percent of cookies would have between 13.8 and 24.2 chips?

Answer 1

95%

Explanation:

You want the percent of cookies having between 13.8 and 24.2 chocolate chips if the number of chocolate chips is normally distributed with a mean of 19 and a standard deviation of 2.6.

Z-score

The z-scores of these limits are found from ...

z = (x -µ)/σ

z = ((-13.8, 24.2) -19)/2.6 = (-5.2, 5.2)/2.6 = (-2, 2)

Probability

The empirical rule tells you that the percent of the distribution within ±2 standard deviations of the mean is 95%.

95% of the cookies will have between 13.8 and 24.2 chips.