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A college chemistry course is divided into two sections.

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by VJesus12 » Thu Apr 12, 2018 9:34 am
A college chemistry course is divided into two sections. In section A, the average score in the final examination was 92. In section B, the average score in the final examination was 84. If the average score of all 40 students in the course was 89, how many students are in section A?

(A) 15
(B) 18
(C) 20
(D) 22
(E) 25

The OA is the option E.

What is the equation that solves this PS question? Help, someone. Thanks in advanced.
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by swerve » Thu Apr 12, 2018 9:51 am
Hi VJesus12,

I solved this questions as follows,

A: Average: B
92: 89: 84

A: B
89-84: 92-89
5 : 3

If total Students are 40.
Then
A: B
25: 15
Option E.

Regards!
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by Scott@TargetTestPrep » Mon Apr 16, 2018 4:15 pm
VJesus12 wrote:A college chemistry course is divided into two sections. In section A, the average score in the final examination was 92. In section B, the average score in the final examination was 84. If the average score of all 40 students in the course was 89, how many students are in section A?

(A) 15
(B) 18
(C) 20
(D) 22
(E) 25
We can let the number of students in section A = A and the number of students in section B = B. Calculating the weighted average of the two sections, we have:

89 = (92A + 84B)/(A + B)

89A + 89B = 92A + 84B

5B = 3A

We also have:

A + B = 40

B = 40 - A

Thus:

5(40 - A) = 3A

200 - 5A = 3A

200 = 8A

A = 25

Answer: E

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