Al, Lew, and Karen pooled their funds to buy a gift for a

swerve wrote:Al, Lew, and Karen pooled their funds to buy a gift for a friend. Al contributed $2 less than 1/3 of the cost of the gift and Lew contributed $2 more than 1/4 of the cost. If Karen contributed the remaining $15, what was the cost of the gift?

A. $24
B. $33
C. $36
D. $43
E. $45

The OA is C.

Please, can anyone explain this PS question? I can't get the correct answer. I need help. Thanks.

Hi swerve,

We can use a shortcut to answer this question and avoid algebraic equations.

If we knew the cost of the gift, we could easily calculate the amounts contributed by Al and Lew.
Since the answer choices represent the cost of the gift, and one of the answer choices must be correct, we can Plug In the Answers.

When Plugging In the Answers, always begin with choice C, unless there is good reason to begin with another choice (for example, in a question that asks for the "least" or "greatest" amount, we might want to begin with choice A or E).
In this question, there's no reason to begin with another choice, so begin with choice C.

If the total cost of the gift was $36, and Al contributed $2 less than 1/3 the total cost, then Al contributed ($36/3) - $2 = $10.
Similarly, if the total cost was $36, and Lew contributed $2 more than 1/4 the total cost, then Lew contributed ($36/4) + $2 = $11.
If Karen contributed the remaining $15, then total cost of the gift was $10 + $11 + $15 = $36.

Since this answer matches the criteria in the question stem, the correct answer must be choice C.

Hope this helps.

Hi All,

We're told that Al, Lew, and Karen pooled their funds to buy a gift for a friend, Al contributed $2 less than 1/3 of the cost of the gift, Lew contributed $2 more than 1/4 of the cost and Karen contributed the remaining $15. We're asked for the total cost of the gift. This question can be solved in a number of different ways, including by TESTing THE ANSWERS.

To start, since the answers are all integers - and the specific dollar figures in the prompt are also integers, we're almost certainly going to need a total that is a multiple of 3 AND of 4 (since the total can be broken into 1/3s and 1/4s). There are two answers that fit that pattern: Answer A and Answer C. Between $24 and $36, Karen's contribution of $15 would make more sense with the larger value, so let's start with Answer C...

Answer C: $36
IF the total was $36, then....
Al contributed (1/3)($36) - $2 = $12 - $2 = $10 and...
Lew contributed $2 + (1/4)($36) = $2 + $9 = $11 and...
Karen contributed $15...
Total = $10 + $11 + $15 = $36
This is an exact match for what we were told, so this MUST be the answer.

Final Answer: C

GMAT assassins aren't born, they're made,
Rich

swerve wrote:Al, Lew, and Karen pooled their funds to buy a gift for a friend. Al contributed $2 less than 1/3 of the cost of the gift and Lew contributed $2 more than 1/4 of the cost. If Karen contributed the remaining $15, what was the cost of the gift?

A. $24
B. $33
C. $36
D. $43
E. $45

We can let the total cost of the gift = n and create the equations.

We see that:

Al contributed: (1/3)n - 2

Lew contributed: (1/4)n + 2

Karen contributed: 15

And so:

(1/3)n - 2 + (1/4)n + 2 + 15 = n

(1/3)n + (1/4)n + 15 = n

Multiplying by 12, we have:

4n + 3n + 180 = 12n

7n + 180 = 12n

180 = 5n

36 = n

Answer: C