# Standard Deviation [closed]

I really need help with this question. If someone could help me it would be great.

A water ride has the minimum height requirement of 5 feet. The average height of children who visit the park is 4 feet 10 inches, with a standard deviation of 2 inches.

1.) What percentage of the children who go to the park qualify to ride?

## closed as off-topic by JMoravitz, Chris Brooks, Matthew Conroy, E. Joseph, NamasteJun 9 '17 at 13:54

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• Hint: Those children who are one standard deviation above the mean height or taller will be allowed to ride the ride (4foot10inches + 2inches = 5foot). What percentage of data in any normally distributed set will be one standard deviation above the mean or greater? – JMoravitz Jun 9 '17 at 3:22

Alright so by the $68-95-99.7$ rule, we have $32\%$ of people are either shorter than $4'6$ or taller than $5'0$
By symmetry of the bell curve, $\boxed{16\%}$ of kids fall under the taller than $5$ feet category and are eligible for the roller coaster. To be more precise, we can use $68.27-95.45-99.73$ to get $\boxed{15.865\%}$