Going into the final exam ,which will count as two-thirds of the final grade,Mike has test scores of 86,80,84,90. What score does mike need on the final in order to earn a B which requires an average score of 80?
Im not sure how to set up the equation..please help if you can.
2007-12-11 10:05:40 · 4 answers · asked by Baby Jet 2 in Science & Mathematics ➔ Mathematics
Take the average of the first 4 scores:
(86 + 80 + 84 + 90) / 4
= 340 / 4
= 85
These count toward *1/3* of the grade.
The remaining score (x) counts toward *2/3* of the grade.
Together they must be more than 80.
(1/3) 85 + (2/3)x ≥ 80
Now solve for x.
I would start by multiplying both sides by 3 to get rid of fractions:
85 + 2x ≥ 240
Subtract 85 from both sides:
2x ≥ 155
Divide both sides by 2:
x ≥ 77.5
So Mike must score at least 77.5 to get an overall grade of B (80 or higher).
2007-12-11 10:19:05 · answer #1 · answered by Puzzling 7 · 1⤊ 0⤋
5x80 =400
400= 86 +80+84 +90 + x
(86 +80) + (84 + 90) + x = 400
(166 + 174) + x = 400
340 + x = 400
400 - 340 = 60
x = 60
And to check your work
86 + 80 + 84 + 90 + 60
__________________= 80
5
2007-12-11 18:25:55 · answer #2 · answered by Thomas B 3 · 0⤊ 0⤋
Let x be final exam, then (86+80+84+90+8x)/12=80.
So, x=77.5
2007-12-11 18:28:36 · answer #3 · answered by yljacktt 5 · 0⤊ 0⤋
86+80+84+90+x
--------------------------- = 80
5
2007-12-11 18:14:37 · answer #4 · answered by Anonymous · 0⤊ 1⤋