Question

3. The amount of coffee in a can from a particular production line is normally distributed with a population mean of 500 grams and a population standard deviation of 20 grams. How many grams of coffee will a can contain 90% of the time?

Answer 1

Solution :

Given that,  

mean = = 500

standard deviation = = 20

Using standard normal table ,

P(Z < z) = 90%

P(Z < 1.28) = 0.90

z = 1.28

Using z-score formula,

x = z * +

x = 1.28 * 20 + 500 = 525.6

525.6 grams of coffee will a can contain 90% of the time.