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Copper and Brass coins

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Copper and Brass coins

by neelgandham » Fri Nov 25, 2011 7:35 am
A bag contains 20 copper and 10 brass coins. If 9 of the coins are removed, how many copper coins are left in the box?

(1) Of the removed coins, the ratio of the number of copper coins to that of brass coins is 2 : 1
(2) Four of the first six coins removed are copper.
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Source: — Data Sufficiency |
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by kmittal82 » Fri Nov 25, 2011 8:54 am
(1)
6 copper coins and 3 brass coins are removed, which leaves 14 copper coins

SUFFICIENT

(2)
four of the first six are copper, remainder could be any combination of copper and bronze coins
INSUFFICIENT

Should be (A)

OA pls?
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by kanwar86 » Fri Nov 25, 2011 9:01 am
IMO, A is correct
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by neelgandham » Fri Nov 25, 2011 3:35 pm
OA A
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by sk8legend408 » Sat Nov 26, 2011 8:52 am
Definitely A. Statement 2 is incorrect because it only contains information about 6 of the 9 coins removed. We need information about all 9 in order to validate the statement.

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by tpr-becky » Mon Nov 28, 2011 11:34 am
Since you know the original numbers of each coins and the total number of coins removed you need to find the number of each kind removed:

Statement 1 - a ratio and an actual total will yield individual numbers -9 coins in ratio of 2:1 - is 3 total parts - thus you will have 6 and 3 and will know how many of each coin.

Statement 2 - this starts to tell you but you have no idea what types of coins are pulled 7,8,9th so you can't solve.

The answer is A.
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