Question

The "Garbage Project" at the University of Arizona reports that the amount of paper discarded by households per week is normally distributed with mean 9.4 lb and standard deviation 4.2 lb. What percentage of households throw out at least 9 lb of paper a week? (Round your answer to one decimal place.)

Answer 1

Answer:

54%

Explanation:

We are given that

S.D=4.2 lb

Mean=$\mu=9.4 lb$

We have to find the percentage of household throw out at least 9 lb of paper  a week.

Normal distribution formula :

$P(X\geq a)=P(z\geq \frac{a-\mu}{\sigma})$

We have a=9

$P(X\geq 9)=P(z\geq \frac{9-9.4}{4.2})=P(z\geq -0.1)$

$P(X\geq 9)=1-P(z$

$P(X\geq 9)=1-0.4602=0.5398\times 100=54$%

Hence, the  percentage of household throw out at least of paper a week=54%