Question

The weights of boxes of rice produced at a factory are normally distributed with a mean of 24 oz and a standard deviation of 1.3 oz. Consider a shipment of 1200 boxes of rice. How many of the boxes will weigh 25 oz or less?

Answer 1

Z - score:
z = X - Mean / Standard deviation
z = ( 25 - 24 ) / 1.3 = 1/1.3 = 0.7692
After that we will use the table for Normal Distribution:
z ( 0.7692 ) = 0.779
0.779 * 1,200 =  935
Answer: 935 boxes will weigh 25 oz or less.