A machine fills jars with 9 ounces of jam. The machine is not exact and jars have a standard deviation of 0.05 ounce. In a lot of 1000 jars, how many jars would you expect to have between 8.9 and 9.1 ounces of jam?

Give the exact answer.

The probability a jar has between 8.9 and 9.1 ounces is at leas

Question

A machine fills jars with 9 ounces of jam. The machine is not exact and jars have a standard deviation of 0.05 ounce. In a lot of 1000 jars, how many jars would you expect to have between 8.9 and 9.1 ounces of jam?

Give the exact answer.

The probability a jar has between 8.9 and 9.1 ounces is at leas

dumbcow · Answer

assuming a normal distribution with mean 9 and std dev .05
9.1 - 9 = 0.1
8.9-9 =-0.1
0.1 is 2 deviations from mean
-0.1 is -2 deviations from mean
using z-table 
P(-2<x<2) = P(x<2) - P(x<-2)
=0.9772 - 0.0228 = 0.9544
0.9544*1000 = 954.4
You would expect 954 jars to have between 8.9 and 9.1 oz of jam