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Al is twice as old as Bill. Five years ago, Al was three times as old
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13 Apr 2021, 05:56
13 Apr 2021, 05:56
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Question Stats:
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Al is twice as old as Bill. Five years ago, Al was three times as old as Bill. How old is Al?
A) 6
B) 10
C) 15
D) 20
E) 30
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
A) 6
B) 10
C) 15
D) 20
E) 30
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
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Re: Al is twice as old as Bill. Five years ago, Al was three times as old
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13 Apr 2021, 06:21
13 Apr 2021, 06:21
1
Carcass wrote:
Al is twice as old as Bill. Five years ago, Al was three times as old as Bill. How old is Al?
A) 6
B) 10
C) 15
D) 20
E) 30
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
A) 6
B) 10
C) 15
D) 20
E) 30
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
We can solve this using two variables or one variable. Let's go with one variable.
Al is twice as old as Bill.
Let x = Al's PRESENT age.
So, 0.5x = Bill's PRESENT age (if Al is TWICE as old as Bill, we can also say that Bill's age is HALF Al's age)
Five years ago, Al was three times as old as Bill. How old is Al?
x - 5 = Al's age 5 YEARS AGO
0.5x - 5 = Bill's age 5 YEARS AGO
We can write: x - 5 = 3(0.5x - 5)
Expand: x - 5 = 1.5x - 15
Subtract x from both sides of the equation: -5 = 0.5x - 15
Add 15 to both sides: 10 = 0.5x
Solve: x = 10/0.5 = 20
Answer: D
gmatclubot
Re: Al is twice as old as Bill. Five years ago, Al was three times as old [#permalink]
13 Apr 2021, 06:21
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