Help! Scoops of ice cream problem

[mtariq]

This is question 1 from the ETS book.

At a certain picnic, each of the guests was served either a single scoop or a double scoop of icecream. 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.
(2) A total of 120 scoops of ice cream were served to all the guests at the picnic.

The answer is (C) both statements are needed.

Now (2) tells us that 120 scoops are served. But a double scoop is really two scoops. So (2) doesn't tell us anything about the number of guests at the picnic. In other words, 120 scoops doesn't mean 120 guests since some of the scoops are double or two scoops. Therefore, I don't see how (2) can be used with (1). I thought the answer was E.

[ananya]

ok,
U eliminated options (A) (B) and (E)

here's how the sum can be solved and the confusion between (C) and (E) can be resolved

suppose there are 10x guests at the picnic

As per statement (1) 6x guests were served a double scoop
4x guests were served a single scoop

As per statement (2)
(6x*2) + (4x*1) = 120
12x + 4x = 120
x = 7.5
Therefore the answer is 6*7.5 = 45 guests were served double scoops.

Obviously you do not need to solve once you have the equation .

Hope that helps you!!!