Chapter 2, Problem T2.9SPT

To determine

To find: that which of the following the best estimates the proportion of light trucks of this model with NOX levels greater than 2 grams per mile.

Answer to Problem T2.9SPT

0.0846

Explanation of Solution

Given:

  $\begin{array}{l}\mu =1.45\\ \sigma =0.40\\ x=2\end{array}$

Formula used:

  $z=\frac{x-\mu }{\sigma }$

Calculation:

  $\begin{array}{c}z=\frac{x-\mu }{\sigma }\\ =\frac{2-1.45}{0.40}\\ =1.375\end{array}$

  $\begin{array}{l}P\left(x>2\right)=P\left(z>1.375\right)\\ =1-P\left(z<1.375\right)\\ =1-0.91545\\ =0.08455\end{array}$

Therefore about 0.0846 of the light trucks of this model have a NOX level greater than 2 grams per mile

Hence, the correct option is (b)