Data Sufficiency

BTGmoderatorDC wrote:A recent lunch meeting at a certain club was attended by members and guests. Each member paid $4 for the lunch and each guest paid $8 for the lunch. How many of the people attending the meeting were members?

(1) A total of 20 people attended the meeting.

(2) A total of $92 was paid for the lunch

OA C

Source: GMAT Prep

Say the number of members was x and the number of guests was y; thus, the total number of people = x + y.

We have to get the value of x.

Let's take each statement one by one.

(1) A total of 20 people attended the meeting.

=> x + y = 20. Can't get the unique value of x. Insufficient.

(2) A total of $92 was paid for the lunch.

=> 4x + 8y = 92. Can't get the unique value of x. Insufficient.

(1) and (2) together

So, we have two unique linear equations (x + y = 20 and 4x + 8y = 92), ensuring unique values of x and y. Sufficient.

There is no need to calculate the value since this is a DS question; in DS question, we just need to to be sure that we would get the unique value.

The correct answer: C

Hope this helps!

-Jay
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