according to a manufacturer, the average weight of a cereal box they produced is 20 ounces with a standard deviation of 0.5 ounce.

a) if a random sample of 1000 boxes are selected, what is the probability that the weight is less than 19.5 ounces?

b) what is the probability that the cereal boxes weigh more than 21 ounces?

c) what is the probability that the cereal boxes weigh between 19.95 and 21.5 ounces?

1 answer

By far the best applet for this kind of work is
davidmlane.com/normal.html

You can enter the data as is, without finding z-scores