kartikshah wrote:In the Adams family there are 7 boys. Each boy is twice as heavy as his next younger brother. If the sum of the boys' weights is 127 pounds, then how much, in pounds, does the oldest boy weigh?
(A) 10
(B) 20
(C) 34
(D) 58
(E) 64
Source: Master GMAT
I set up an equation x+2x+4x+....64x = 127
Any quicker way to solve?
ALWAYS LOOK AT THE ANSWER CHOICES.
The sum of the weights is an integer.
The answers represent the weight of the oldest boy.
Since each boy is twice as heavy at the next youngest boy, the correct answer must be a value that can be divided by 2 six times.
Since 2� = 64, the only viable answer choice is
E:
64+32+16+8+4+2+1 = 127.
Success!
The correct answer is
E.
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