Your quiz grades are 78 72 87 and 90 what score on the fifth quiz will make your average quiz grade at least 82

Quiz grades: 78, 72, 87, 90, x = ?

If you would like to know what score on the fifth quiz (x = ?) will make your average quiz grade at least 82, you can calculate this using the following steps:

(78 + 72 + 87 + 90 + x) / 5 >= 82
(327 + x) / 5 >= 82     /*5
327 + x >= 82 * 5
x >= 410 - 327
x >= 83

Result: You have to get at least 83 on the fifth quiz.