You have scored 7, 10, 8, and 9 on four quizzes. You are trying to find the score you need on the fifth quiz so that your mean score is 8. The definition of means is to add all of the numbers and divide them by how many numbers you added. Therefore, 7+10+8+9 = 34. You need to add the fifth score, which will be "x". (34+x)/5 = 8. 34 + x = 40. x = 6. Thus, your answer is 6.
