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
the OA is 188. how?
weight problem
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Solution:sportypk 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
the OA is 188. how?
This problem can be solved as a simple word problem in which we must convert words to math. Before we create our equations, we want to define some variables.
J = Jake's current weight, in pounds
S = Sister's current weight, in pounds
We are told that "If Jake loses 8 pounds, he will weigh twice as much as his sister." We put this into an equation:
J - 8 = 2S
We can isolate J by adding 8 to 2S:
J = 2S + 8 (Equation 1)
Next, we are told that "Together they now weigh 278 pounds." We can also put this into an equation.
J + S = 278 (Equation 2)
To solve this equation, we can substitute 2S + 8 from Equation 1 for the variable J in Equation 2:
2S + 8 + S = 278
3S = 270
S = 90
We now know that the sister weighs S = 90 pounds, and we can plug that value into either equation to determine J. Let's plug 90 for S into equation 2:
J + 90 = 278
J = 188
Answer: E
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Here's a solution that uses one variable.sportypk 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
Let x = Jake's present weight in pounds
So, x - 8 = Jake's hypothetical weight IF he were to lose 8 pounds
If Jake loses 8 pounds, he will weigh twice as much as his sister.
In other words, the sister weighs HALF as much as Jake's hypothetical weight of x - 8 pounds
So, (x - 8)/2 = sister's present weight
Together they NOW weigh 278 pounds.
So, Jake's present weight + sister's present weight = 278
So, x + (x - 8)/2 = 278
Eliminate fractions by multiplying both sides by 2 to get: 2x + (x - 8) = 556
Simplify: 3x - 8 = 556
Add 8 to both sides: 3x = 564
Solve: x = [spoiler]188 = E[/spoiler]
Cheers,
Brent
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ALWAYS KEEP YOUR EYE ON THE ANSWER CHOICES.sportypk 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
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.
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Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
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Sweeeeeeeeeet!GMATGuruNY wrote:ALWAYS KEEP YOUR EYE ON THE ANSWER CHOICES.sportypk 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
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.
Cheers,
Brent
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Hi All,
The answer choices in this question are 'spread out' in such a way that we can get to the correct answer with just a bit of logical thinking.
We're told that the total weight of Jake and his sister = 278 pounds. We're also told that if Jake LOST 8 pounds, he would TWICE as much as his sister....
This means that Jake weighs MORE than twice his sister RIGHT NOW. Since the total is 278 pounds, Jake's weight MUST make up MOST of that total weight (a lot more than half). There's only one answer that fits....
Final Answer: E
GMAT assassins aren't born, they're made,
Rich
The answer choices in this question are 'spread out' in such a way that we can get to the correct answer with just a bit of logical thinking.
We're told that the total weight of Jake and his sister = 278 pounds. We're also told that if Jake LOST 8 pounds, he would TWICE as much as his sister....
This means that Jake weighs MORE than twice his sister RIGHT NOW. Since the total is 278 pounds, Jake's weight MUST make up MOST of that total weight (a lot more than half). There's only one answer that fits....
Final Answer: E
GMAT assassins aren't born, they're made,
Rich
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- Brent@GMATPrepNow
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Another sweeeeet answer![email protected] wrote:Hi All,
The answer choices in this question are 'spread out' in such a way that we can get to the correct answer with just a bit of logical thinking.
We're told that the total weight of Jake and his sister = 278 pounds. We're also told that if Jake LOST 8 pounds, he would TWICE as much as his sister....
This means that Jake weighs MORE than twice his sister RIGHT NOW. Since the total is 278 pounds, Jake's weight MUST make up MOST of that total weight (a lot more than half). There's only one answer that fits....
Final Answer: E
GMAT assassins aren't born, they're made,
Rich
And here I'm using algebra like some sucker!!
I love seeing how many approaches one can take with a GMAT math question!!!
I've already reached my exclamation mark quota for the day, so I hope no one else presents more awesome approaches.
Cheers,
Brent
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Mitch's solution is obviously fastest, but there is a no-variable solution we can use if the answer choices don't allow for any trick: if Jake loses 8 pounds, then together they'll weigh 270 pounds, and if Jake would then weigh twice as much as his sister, the ratio of their weights is 2 to 1, so Jake would weigh 2/3 of 270, or 180 pounds. Add back the 8, and 188 is the answer.
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com
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