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 8 lb of paper a week?

Answer 1

62.93%

Explanation:

We know that mean=9.4 lb and standard deviation=4.2 lb.

We have to find P(x≥8).

P(x≥8)=P((x-mean)/sd≥(8-9.4)/4.2)

P(x≥8)=P(z≥(-0.3333)

Rounding z score to 0.33

P(x≥8)=P(-0.33<z<0)+P(0<z<∞)

Using normal area table and we get P(-0.33<z<0)=0.1293

P(x≥8)=0.1293+0.5

P(x≥8)=0.6293

The percentage of households throw out at least 8 lb of paper a week is 62.93%