AIM TO CRACK GMAT wrote:Each of 435 bags contains at least one of the following three items: raisins, almonds, and peanuts. The number of bags that contain only raisins is 10 times the number of bags that contain only peanuts. The number of bags that contain only almonds is 20 times the number of bags that contain only raisins and peanuts. The number of bags that contain only peanuts is one-fifth the number of bags that contain only almonds. 210 bags contain almonds. How many bags contain only one kind of item?
A 256 B 260 C316 D320 E350
Let R = only raisins, P = only peanuts, , RP = raisins and peanuts, A = only almonds.
T = 435.
The total number of bags with almonds = 210.
Thus, all of the OTHER bags contain raisins, peanuts, or both:
R+P+RP = 435-210 = 225.
The number of bags that contain only raisins is 10 times the number of bags that contain only peanuts:
R : P = 10:1.
The number of bags that contain only peanuts is one-fifth the number of bags that contain only almonds:
P = (1/5)A, implying that P:A = 1:5.
Combining R : P = 10:1 and P:A = 1:5, we get:
R : P : A = 10:1:5.
The number of bags that contain only almonds is 20 times the number of bags that contain only raisins and peanuts:
Thus, the value of A must be a multiple of 20:
R : P : A = 4(10:1:5) = 40:4:20.
Since the sum of the parts of this ratio = 40+4+20 = 64, the value of R+P+A must be a MULTIPLE OF 64.
Of the answer choices, only A and D are multiples of 64.
Since all of the values in the problem (435, 210, 225) are multiples of 5, the correct answer is also almost certainly a multiple of 5.
Answer choice D: R+P+A = 320
Since 320/64 = 5, the multiplier for R : P : A = 40:4:20 is 5:
R : P : A = 5(40:4:20) = 200:20:100.
Here, R=200, P=20, A=100.
Since R+P+RP = 225, and in the ratio above R+P = 220, RP = 5.
If
D is the correct answer, the value of A will be 20 times the value of RP:
A/RP = 100/5 = 20.
Success!
The correct answer is
D.
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