Question

The distribution of caffeine in grande cups of starbucks coffee is normal with a mean of 142 mg and a standard deviation of 2 mg. what percentage of grande coffees have a caffeine content of between 139 and 142.5 mgs? select one:

a. 0.5319
b. 0.5987
c. 0.0668
d. 0.3418

Answer 1

`P(139<X<142.5)=P\left(\frac{139-142}2<\frac{X-142}2<\frac{142.5-142}2\right)`

`=P(-1.5<Z<0.25)\approx0.5319`