Al is twice as old as Bill. Five years ago, Al was three times as old

Question

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

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ManifestDreamMBA · Answer

Al 
 Bill 
 Notes 
 
  Current 
 2B 
 B 
 Al is twice as old as Bill 
 
  Cureent-5 
 2B-5 
 B-5 
 Five years ago, Al was three times as old as Bill

2B-5 = 3*(B-5)
B=10
A=2B=20

Dereno · Answer

Current scenario:

Let the current ages of AI and Bill be an and b respectively.

a = 2*b

Five years ago , AI is three times as old as Bill.

(a-5) = 3*(b-5)

a-5 = 3b -15

Substitute a =2b

2b -5 = 3b-15

b = 10

Then a = 2*b = 2*10 =  20

Option D

Missinga · Answer

Al is twice as old as Bill. Five years ago, Al was three times as old as Bill. How old is Al?
A=2B
A-5= 3(B-5)
A-5=3B-15
A-5+15=3(A/2)
(A+10)2=3A
3A-2A=20
A=20

Answer: D

GraemeGmatPanda · Answer

Another way of doing this is looking at the answers and thinking about divisibility

Al is twice as old as Bill. So Al's age cannot be odd. --> This rules out A

Five years ago, Al was three times as old as Bill. This means that if you subtract 5 from the answer, it will be a multiple of 3

B) 10 - 5 = 5 --> not divisible by 3
C) 15 - 5 = 10 --> not divisible by 3
D) 20 - 5 = 15 --> divisible by 3
E) 30 - 5 = 25 --> not divisible by 3

So Answer D is the only one that works!
ʕ•ᴥ•ʔ

ravi1522 · Answer

Hello,
Lets AI as A and Bill as B
A=2B

five years ago 
A-5=3(B-5)

so when we solve it 
B=10
so AI will be 20

Hence option D is correct

Al is twice as old as Bill. Five years ago, Al was three times as old

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	Al	Bill	Notes
Current	2B	B	Al is twice as old as Bill
Cureent-5	2B-5	B-5	Five years ago, Al was three times as old as Bill

GMAT Problem Solving (PS) Questions

Al is twice as old as Bill. Five years ago, Al was three times as old

Prep Toolkit

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My Rewards