Whats the function to this math prob

Assume that the weights of quarters are normally distributed with a mean of 5.67 g and a standard deviation 0.070 g. a vending machine will only accept coins weighing between 5.48 g and 5.82 g. what percentage of legal quarters will be rejected? round your answer to two decimal places.

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

What is the distance between point a and b