posted by Jessica on .
Drivers pay an average of (mean $690) per year for automobile insurance the distribution of insurance payments is approximately normal with a standard deviation of 110 dollars. What proportion of drivers pay more than 100 dollars per year for insurance?
z = (x - mean)/sd
x = 100
mean = 690
sd = 110
Plug the values into the formula, then use a z-table to determine the proportion.
I hope this will help get you started.