Question

The distribution of cholesterol levels in teenage boys is approximately normal with and (Source: U.S. National Center for Health Statistics). Levels above 200 warrant attention. Find the probability that a teenage boy has a cholesterol level greater than 225.

Answer 1

0.033 is the probability that a teenage boy has a cholesterol level greater than 225.

Explanation:

The following information is missing in the question:

Mean, μ = 170

Standard Deviation, σ = 30

Using the given information, we may solve the question as:

We are given that the distribution of distribution of cholesterol levels in teenage boys is a bell shaped distribution that is a normal distribution.

Formula:

`z_(score) = \displaystyle(x-\mu)/(\sigma)`

a) P( cholesterol level greater than 225)

P(x > 225)

`P( x > 225) = P( z > \displaystyle(225 - 170)/(30)) = P(z > 1.833)`

`= 1 - P(z \leq 1.833)`

Calculation the value from standard normal z table, we have,

`P(x > 225) = 1 - 0.967= 0.033 = 3.3\%`

0.033 is the probability that a teenage boy has a cholesterol level greater than 225.