In a class in which the final course grade depends entirely

Last updated: 7/16/2022

In a class in which the final course grade depends entirely on the average of four equally weighted 100-point tests, David has scored 76, 80, and 84 on the first three. What range of scores on the fourth test will give David a C for the semester (an average between 70 and 79, inclusive)? Assume that all test scores have a non-negative value.