The average scores in two classes A and B in a particular te

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The average scores in two classes A and B in a particular te [#permalink]

28 Dec 2012, 05:48

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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

Cheers,
Taz

[Reveal] Spoiler: OA

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Re: The average scores in two classes A and B in a particular te [#permalink]

29 Dec 2012, 12:40

tabsang wrote:

Let number of students in class A be "a" and number of students in class B be "b"

Combined average = (60*a + 75*b)/ (a + b)
= (60*(a/b) + 75)/( 1 + (a/b))
So, if we know the ratio of number of students in class A and B then we can find the answer

STAT1
The number of students in class A is 50% more than the number of students in class B.
=> a = 1.50 * b
=> a/b = 1.5
SUFFICIENT!

STAT2
The number of students in the two classes A and B are in the ratio of 3:2
=> a/b = 3:2 = 1.5
SUFFICIENT!

Hence, Answer will be D
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Re: The average scores in two classes A and B in a particular te [#permalink]

30 Dec 2012, 05:00

tabsang wrote:

Important thing in weighted average problem is realizing that ratio of the two quantity will suffice.

1: A = 1.5B so A/B = 3/2
2: A/B = 3/2

Re: The average scores in two classes A and B in a particular te [#permalink] 30 Dec 2012, 05:00

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The average scores in two classes A and B in a particular te

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The average scores in two classes A and B in a particular te

The average scores in two classes A and B in a particular te

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