A machine is designed to fill 16-ounce bottles of shampoo. When the machine is working properly, the amount poured into the bottles follows a normal distribution with mean 16.05 ounces with a standard deviation of .1005 ounces. If four bottles are randomly selected each hour and the number of ounces in each bottle is measured, then 95% of the means calculated should occur in what interval?

Between 15.95 ounces and 16.15 ounces.

Step-by-step explanation:

We have the following value m, being the mean, sd, being the standard deviation and n, the sample size:

m = 16.05

sd = 0.1005

n = 4

We apply the formula of this case, which would be:

m + - 2 * sd / (n ^ 1/2)

In this way we create a range, replacing we have:

16.05 + 2 * 0.1005 / (4 ^ 1/2) = 16.1505

16.05 - 2 * 0.1005 / (4 ^ 1/2) = 15.9495

Which means that 95% of all samples are between 15.95 ounces and 16.15 ounces.

area of part 1:

a1=base*height/2=(8+2)*(8-2-2-1)/2=10*3/2=15 ft^2

area of part 2:

a2=length*width=(8+2)*1=10 ft2

area of part 3:

a3=length*width=8*2=16 ft2

total shaded area : a1+a2+a3=41 ft2

total area of the reactangle : a=16*8=128 ft2

total area of the nonshaded region : 128-41=87 ft2