SOLUTION: A student scored five points more on the second quiz than he did on the first quiz. He scored eleven points lower on the third quiz than on the first one. If the average of all thr
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Question 404435: A student scored five points more on the second quiz than he did on the first quiz. He scored eleven points lower on the third quiz than on the first one. If the average of all three is 70. What was the score on the first quiz? Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! A student scored five points more on the second quiz than he did on the first quiz.
He scored eleven points lower on the third quiz than on the first one.
If the average of all three is 70.
What was the score on the first quiz?
:
let x = 1st quiz score
let y = 2nd quiz
let z = 3rd quiz
:
Write an equation for each statement:
;
"A student scored five points more on the second quiz than he did on the first quiz."
y = (x+5)
:
" He scored eleven points lower on the third quiz than on the first one."
z = (x-11)
:
" If the average of all three is 70. " = 70
Multiply both sides by 2
x + y + z = 3(70)
x + y + z = 210
Replace y with (x+5) and z with (x-11)
x + (x+5) + (x-11) = 210
3x - 6 = 210
3x = 210 + 6
x =
x = 72 is the score on the 1st quiz
:
:
Confirm this
(72 + 77 + 61) /3 = 70
