(1.9 - 2.5)/0.4 =
(3.1 - 2.5)/0.4 =
If these formulas are not familiar to you, yiou need to back up a chapter and give it another go.
Can't figure out how to solve this for my math test due on Tuesday. Any help would be wonderful!
Testing indicates that the lifetimes of a new shipment of 500 storage batteries are approximately normally distributed with a mean of 2.5 years and a standard deviation of 0.4 years. How many of the storage batteries would you expect to last between 1.9 and 3.1 years?