Question

Let X equal the distribution of the possible BMIs in children with reported weight problems aged 5-18 years old. Suppose this distribution was approximately normal with mean of 21.7 and standard deviation of 1.34.

• What BMI level correspond to the top 8%?

		10.22
		23.89
		None of the other choices represents a suitable response
		1.41
		23.6

Answer 1

Solution:-

Given that,

mean = = 21.7

standard deviation = = 1.34

Using standard normal table,

P(Z > z) = 8%

= 1 - P(Z < z) = 0.08  

= P(Z < z) = 1 - 0.08

= P(Z < z ) = 0.92

= P(Z < 1.41) = 0.92  

z = 1.41

Using z-score formula,

x = z * +

x = 1.41 * 1.34 + 21.7

x = 23.6