An instructor gives 3 initial exams and a final exam for a certain course. The average of the 3 initial exams was weighted 3.5 and the final exams is weighted 2/5. A student received initial exam grades of 72,73, and 80, and a final grade of x. If the students weighted average for the course was 79, what is the value of x?
a. 90
b. 87
c. 85
d. 84
e. 81
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Problem Solving- Weighted Average
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AndreaV424
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truplayer256
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Average of 72,73, and 80= 145+80/(3)= 225/3= 75.
75*3/5+2/5(x)= 79
45+2/5(x)=79
34*5/2=x
x=17*5= 85
C
75*3/5+2/5(x)= 79
45+2/5(x)=79
34*5/2=x
x=17*5= 85
C
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[email protected]
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Thanks trueplayer,
But if you could please explain why you multiplied 75 by 3/5?
Regards,
Niharika.
But if you could please explain why you multiplied 75 by 3/5?
Regards,
Niharika.
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GMATGuruNY
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The fraction in red above reflects the intent of the problem.AndreaV424 wrote:An instructor gives 3 initial exams and a final exam for a certain course. The average of the 3 initial exams was weighted 3/5 and the final exams is weighted 2/5. A student received initial exam grades of 72,73, and 80, and a final grade of x. If the students weighted average for the course was 79, what is the value of x?
a. 90
b. 87
c. 85
d. 84
e. 81
Since the final grade of x must account for 2/5 of the course -- in other words, for 2 of every 5 grades -- let the 5 grades be 72, 73, 80, x, x.
Since the average of the 5 grades is 79, we get:
Sum of the 5 grades = (number)(average) = 5*79 = 395.
Thus:
72+73+80+x+x = 395
2x = 170
x = 85.
The correct answer is C.
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Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
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