How to find equation of a straight line

Is a positive integer raised to a negative power always positive

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.

Ijust need to see how to do this. so you don’t have to answer all of them just a step by step explanation of one.