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D.S. Dhamaka I : Averages.

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D.S. Dhamaka I : Averages.

by tabsang » Fri Dec 28, 2012 4:18 am
The average scores in two classes A and B in a particular test are 60 and 75 respectively. What is the average score of the two classes taken together?

(1) The number of students in class A is 50% more than the number of students in class B.
(2) The number of students in the two classes A and B are in the ratio of 3:2

OA coming up!!
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by Anurag@Gurome » Fri Dec 28, 2012 5:27 am
tabsang wrote:The average scores in two classes A and B in a particular test are 60 and 75 respectively. What is the average score of the two classes taken together?

(1) The number of students in class A is 50% more than the number of students in class B.
(2) The number of students in the two classes A and B are in the ratio of 3:2
Say, number of students in class A and B are x and y, respectively.
Hence, the average score of the two classes taken together = (60x + 75y)/(x + y)

Statement 1: x = 50% more than y = 150% of y = (150/100)*y = 3y/2
Hence, the average score of the two classes taken together = (60x + 75y)/(x + y) = (60*(3y/2) + 75y)/(3y/2 + y) = Some number independent of x and y

Sufficient

Statement 2: 2x = 3y --> Same as statement 1

Sufficient

The correct answer is D.
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by tabsang » Fri Dec 28, 2012 7:31 am
OA:[spoiler](D)[/spoiler]
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by ritind » Sun Dec 30, 2012 2:34 am
If you look closely at both the statements, you'll find out that both of them are saying the same stuff.
So OA shld be either D or E
Its a simple question of weighted avg.
OA is D
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