A student has scores of 70, 75 and 81 on her three exams what score does she need on her fourth exam to give her an average of 80 or better?
2007-02-14 06:10:36 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Geography
You have to count how many exams she's taken so far, which is 3, and add 1 to make 4. Now multiply 80 by 4 and get 320. That's what all her grades have to add up to. So subtract 320-70-75-81 and you get 94. She has to get at least a 94.
2007-02-14 06:14:10 · answer #1 · answered by andthendougsaid 2 · 0⤊ 0⤋
80*4 =70+75+81+x
x=320 - 226 = 94
She needs 94 or more
2007-02-14 14:31:40 · answer #2 · answered by imamulleith 2 · 0⤊ 0⤋
80 * 4 = 320
70 + 75 + 81 + x = 320
226 + x = 320
x = 320 - 226
x = 94
You at least need 94 in ur last exam
2007-02-14 14:39:32 · answer #3 · answered by Yash Y 2 · 0⤊ 0⤋
let x be the grade you need to get
(70 +75 + 81 + x)/4 = 80
70 +75 + 81 + x= 80 * 4
226 + x = 320
x = 94
2007-02-14 14:14:38 · answer #4 · answered by SPB 6 · 0⤊ 0⤋
94
2007-02-14 14:18:22 · answer #5 · answered by They call me ... Trixie. 7 · 0⤊ 0⤋