cost of office dinner

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cost of office dinner

by gibran » Thu May 15, 2008 9:30 am
The total cost of an office dinner was shared equally by k of the n employees who attended the dinner. What was the total cost of the dinner?
(1) Each of the k employees who shared the cost of the dinner paid $19.
(2) If the total cost of the dinner had been shared equally by k + 1 of the n employees who attended the dinner, each of the k + 1 employees would have paid $18.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Source: — Data Sufficiency |

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by codesnooker » Thu May 15, 2008 9:54 am
Answer is (C).

Here n is given just to confuse us.

According to statement 1, Total Cost = $(19 X K). You cannot determine the cost of dinner by this, as its a linear equation of two variables. Therefore, INSUFFICIENT.

According to statement 2, Total Cost = $((K + 1) X 18). Again, you cannot determine the cost of dinner by this, as its a linear equation of two variables. Therefore, INSUFFICIENT.

Now if you take both statements together, then you have two equations of two unknown common variables. Hence, you can easily determine the answer. (No need to calculate in real GMAT). Hence SUFFICIENT.

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by bhumika.k.shah » Fri Jan 22, 2010 3:12 am
i agree no need to calculate since its a DS question.But had it been a PS question how would we show that both statements together can give u an answer???