The quiz grades of a math class are given. 81, 75, 68, 97, 69, 81, 89, 74, 75, 82, 91, 90 The grades are normally distributed with a mean of 81 and a standard deviation of 9. 2 What is the z-score of the lowest grade in the quiz?​

The water has been on the stove y=9.5x+62.1 after how many minutes will the tempature be 138.1 f

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.

Yesterday i ran 5 miles. today, i ran 3.7 miles. did my percent increase, decrease or is it a percent error? plz i need