its a story problem. I got the correct answer (at least I think it's the correct answer) but I didn't use an algebraic formula. Can you explain how to do the problem in algebraic terms. THANKS:
Geri had an average of 80% on four tests. What score must she get on the next test to raise her average to 83%.
I know the problems not too hard, but whenever I have to think of a way to write it algebraically it always seems to take forever. UGH! maybe I'm just not very good at these things.
How would you do it algebraically?
2007-10-23 16:21:45 · 10 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
xone + xtwo + xthree + xfour / 4 = 80
xone + xtwo + xthree + xfour = 80*4 = 320
let y= xone + xtwo + xthree + xfour
y + xfive / 5 = 83
320 +xfive / 5 = 83
mult by 5
320 +xfive = 415
-320 -320
xfive = 95
2007-10-23 16:28:16 · answer #1 · answered by a c 7 · 0⤊ 0⤋
X = Score Needed On 5th Test
(80 x 4) +X = (83 x 5)
320 + X = 415
X = 415 - 320
X = 95
2007-10-23 18:07:13 · answer #2 · answered by Alan S 6 · 0⤊ 0⤋
X + (80 x 4) = (83 x 5)
X + 320 = 415
X = 95
2007-10-23 16:29:50 · answer #3 · answered by Patti D 2 · 0⤊ 0⤋
Multiply 80 by 4 to get the total number of test points.
Then set up the equation using x as the fifth test score.
(320 + x)/5 = 83
Multiply by 5 on both sides and get this:
320 + x = 415
Subtract 320 from both sides.
x = 95
2007-10-23 16:28:53 · answer #4 · answered by Anonymous · 0⤊ 0⤋
[21]
4*80+x=5*83
{explanation - Let x be the marks she has to get in her 5 th test.In the earlier 4 tests she has got 4*80 or 320 marks.
So this plus x should be equal to 5*83 or 415 marks
So you may write the equation also as
320+x=415]
2007-10-23 16:28:49 · answer #5 · answered by alpha 7 · 0⤊ 0⤋
% total after 4 tests = 320
Let next mark = x %
Total after 5 tests = 320 + x %
(320 + x) / 5 = 83
320 + x = 415
x = 95%
She must score 95 %
(but can she do it?!!!)
2007-10-24 03:54:52 · answer #6 · answered by Como 7 · 0⤊ 0⤋
The average so far is
(score1+score2+score3+score4)/4 = 80
which tells us that the toal of the first four scores is
score1+score2+score3+score4 = 320
The desired average is
(score1+score2+score3+score4+score5)/5 = 83
([score1+score2+score3+score4]+score5)/5 = 83
(320+score5)/5 = 83
320+score5 = 415
score5 = 95
2007-10-23 16:30:41 · answer #7 · answered by richarduie 6 · 0⤊ 0⤋
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2016-10-07 12:15:46 · answer #8 · answered by raj 4 · 0⤊ 0⤋
i think he must get at least 85% to get an averange of 83%
2007-10-23 16:27:48 · answer #9 · answered by Vida Joy 3 · 0⤊ 1⤋
Here: (s1+s2+s3+s4)/4=0.8
so: s1+s2+s3+s4=3.2
Now we want: (s1+s2+s3+s4+s5)/5=0.83
substitute: (3.2+s5)/5=0.83
so: s5+3.2=4.15
hence: s5=0.95 or 95%
Good luck!
2007-10-23 16:31:16 · answer #10 · answered by outdoorguy 1 · 0⤊ 0⤋