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28 Sep 2021, 21:03
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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:
98% (01:04) correct
2%
(02:10)
wrong
based on 49
sessions
History
Date
Time
Result
Not Attempted Yet
Today is Shawn's 14th birthday and his father's 50th birthday. How many years must pass before Shawn's father will be twice as old as Shawn will be at that time?
A) 14
B) 18
C) 20
D) 22
E) 25
A) 14
B) 18
C) 20
D) 22
E) 25
28 Sep 2021, 22:44
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MonkeyDDes
Solution:
Today is Shawn's 14th birthday and his father's 50th birthday. This means Shawn is 14 years old and his father is 50 years old today.
Let us assume that after n years, Shawn's father will be twice as old as Shawn will be.
So, after n years, Shawn's age \(= 14+n\) and his father's age \(= 50+n\).
We can write: \(50+n=2(14+n)\)
\(\Rightarrow 50+n=28+2n\)
\(\Rightarrow 50-28=2n-n\)
\(\Rightarrow 22=n\)
\(\Rightarrow n=22\)
Hence the right answer is Option D.
General Discussion
29 Sep 2021, 07:38
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MonkeyDDes
Another approach is to simply test each answer choice...
A) 14
So, in 14 years, Shawn's age = 14 + 14 = 28, and his father's age = 50 + 14 = 64
Since 64 does not equal TWICE 28, answer choice A is incorrect.
B) 18
So, in 18 years, Shawn's age = 14 + 18 = 32, and his father's age = 50 + 18 = 68
Since 68 does not equal TWICE 32, answer choice B is incorrect.
C) 20
So, in 20 years, Shawn's age = 14 + 20 = 34, and his father's age = 50 + 20 = 70
Since 70 does not equal TWICE 34, answer choice C is incorrect.
D) 22
So, in 22 years, Shawn's age = 14 + 22 = 36, and his father's age = 50 + 22 = 72
Since 72 equals TWICE 36, answer choice D CORRECT.
Answer: D
