fskilnik@GMATH wrote:GMATGuruNY wrote:BTGmoderatorDC wrote:If Jake loses 8 pounds, he will weigh twice as much as his sister. Together they now weigh 278 pounds. What is Jake's present weight, in pounds?
(A) 131
(B) 135
(C) 139
(D) 147
(E) 188
ALWAYS KEEP YOUR EYE ON THE ANSWER CHOICES.
If Jake loses 8 pounds, he will weigh twice as much as his sister.
j-8 = 2s
j =
2s + 8 =
even + even = even.
Since Jake's weight
must be an EVEN VALUE, the correct answer is
E.
Good idea, but the final check to see whether the *potential* answer satisfies the question stem is necessary.
I explain: with exactly the same question stem, but 366 in the place of 278, we would come to the wrong alternative choice.
(If sister weights 89.5 pounds, twice her weight is 179, Jake could weight 187 pounds and the argument shown in red fails.)
Regards,
Fabio.
The sum of Jake's weight and his sister's weight is an INTEGER VALUE.
The answer choices indicate that Jake's weight is an INTEGER VALUE.
Implication:
The sister's weight must also be an integer value.
Thus, the value in red -- 89.5 -- is not a valid option for the sister's weight.
Given the conditions in the problem, Jake's weight must be an EVEN INTEGER.
As a result, the only viable answer choice is
E.
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