SOLUTION: Emilía has an average of 70 on 4 different tests. If the lowest score is dropped, her average rises to 90. What is the lowest score?

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Question 1210373: Emilía has an average of 70 on 4 different tests. If the lowest score is dropped, her average rises to 90. What is the lowest score?
Found 3 solutions by josgarithmetic, greenestamps, math_tutor2020:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
%28w%2Bx%2By%2Bz%29%2F4=70
andthen
%28x%2By%2Bz%29%2F3=90, assuming w is lowest score

system%28w%2Bx%2By%2Bz=280%2Cx%2By%2Bz=270%29
But so many variables are not really necessary for this.

Let r=x%2By%2Bz.
system%28w%2Br=280%2Cr=270%29
highlight%28w=10%29

Answer by greenestamps(13198) About Me  (Show Source):
You can put this solution on YOUR website!


4 tests with an average of 70; total points 70*4 = 280.

3 tests with an average of 90; total points 90*3 = 270.

The number of points on the test that is dropped is 280-270 = 10.

ANSWER: 10

Answer by math_tutor2020(3816) About Me  (Show Source):
You can put this solution on YOUR website!

x = sum of the three scores after the lowest score was dropped, i.e. we ignore the lowest score
x/3 = 90 = mean of those three scores
x = 3*90 = 270

y = lowest score that was dropped
x+y = sum of four test scores
(x+y)/4 = 70
(270+y)/4 = 70
270+y = 4*70
270+y = 280
y = 280-270
y = 10

Answer: 10