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Stoneface
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Frank is 15 years younger then John. In 5 years John will be 11 Mar 2012, 14:54
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D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

5% (low)

Question Stats:

87% (01:41) correct 13% (02:27) wrong based on 527 sessions

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Frank is 15 years younger then John. In 5 years John will be twice as old as Frank. How old will Frank be in four years?

A. 8
B. 10
C. 12
D. 14
E. 16
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D
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Bunuel
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Frank is 15 years younger then John. In 5 years John will be 11 Mar 2012, 15:04
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Stoneface
Frank is 15 years younger then John. In 5 years John will be twice as old as Frank. How old will Frank be in four years?

a 8
b 10
c 12
d 14
e 16
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Frank is 15 years younger then John --> F+15=J;

In 5 years John will be twice as old as Frank (in 5 year John will be J+5 years old and Frank will be F+5 years old) --> J+5=2*(F+5) --> (F+15)+5=2*(F+5) --> F=10;

In 4 years Frank will be 10+4=14 years old.

Answer: D.

Hope it's clear.
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Frank is 15 years younger then John. In 5 years John will be 11 Mar 2012, 15:34
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This is where I made my mistake: J+5=2*(F+5). I was working J+5=2*F. Thanks!
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Frank is 15 years younger then John. In 5 years John will be 13 Mar 2012, 16:32
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I like to work these kind of problems in columns

F | J
----------------------
Now X-15 | X

In 5 years X-15+5=X-10 | X+5

twice as old means X+5=X-10=>X=25

But what we want is X-15+4 so 25-15+4=D


PS: The column is not clear enough in the post but I hope it is obvious
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Frank is 15 years younger then John. In 5 years John will be 07 Jan 2017, 15:26
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F = J-15
2(F+5) = J+5 >> 2F+10=J+5

So. F= 10

In four years,

F+4=14
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Frank is 15 years younger then John. In 5 years John will be 18 Aug 2018, 19:21
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Stoneface
Frank is 15 years younger then John. In 5 years John will be twice as old as Frank. How old will Frank be in four years?

A. 8
B. 10
C. 12
D. 14
E. 16
Show more

We can create the equations:

F + 15 = J

and

J + 5 = 2(F + 5)

J + 5 = 2F + 10

J = 2F + 5

Substituting, we have:

F + 15 = 2F + 5

10 = F

So in 4 years Frank will be 14.

Answer: D
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Frank is 15 years younger then John. In 5 years John will be 19 Aug 2018, 00:59
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Stoneface
Frank is 15 years younger then John. In 5 years John will be twice as old as Frank. How old will Frank be in four years?

A. 8
B. 10
C. 12
D. 14
E. 16
Show more
Attachment:
Capture.PNG
Capture.PNG [ 3.18 KiB | Viewed 20840 times ]
\(j + 5 = 2(j - 10)\)

\(j + 5 = 2j - 20\)

Or, \(j = 25\) ,

So, Frank's age after 4 years will be \(j - 11\) , ie \(25 - 11 = 14\), Answer must be (D)
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Frank is 15 years younger then John. In 5 years John will be 04 Nov 2025, 00:41
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