At a certain picnic, each of the guests was served either a

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At a certain picnic, each of the guests was served either a single scoop or a double scoop ice-cream. How many of the guests were served a double scoop of ice-cream?

(1) At the picnic, 60 percent of the guests were served a double scoop of ice-cream.

(2) A total of 120 scoops of ice-cream were served to all the guests at the picnic.

OA C

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by GMATGuruNY » Sat Jun 15, 2019 2:38 am

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BTGmoderatorDC wrote:At a certain picnic, each of the guests was served either a single scoop or a double scoop ice-cream. How many of the guests were served a double scoop of ice-cream?

(1) At the picnic, 60 percent of the guests were served a double scoop of ice-cream.

(2) A total of 120 scoops of ice-cream were served to all the guests at the picnic.
Let D = the double-scoop guests and S = the single-scoop guests.
What is value of D?

Statement 1:
Since 60% received a double-scoop, the remaining 40% received a single scoop.
Thus:
D/S = 60%/40% = 3/2
No way to solve for D.
INSUFFICIENT.

Statement 2:
Since the D double-scoop guests each received 2 scoops, while the S single-scoop guests each received 1 scoop, we get:
2D + S = 120
No way to solve for D.
INSUFFICIENT.

Statements combined:
Since we have two variables (D and S) and two distinct linear equations (D/S=3/2 and 2D+S=120), we can solve for the two variables.
Thus, the value of D can be determined.
SUFFICIENT.

The correct answer is C.
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