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01 Dec 2015, 04:28
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C
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Difficulty:
25%
(medium)
Question Stats:
77% (02:21) correct
23%
(02:05)
wrong
based on 117
sessions
History
Date
Time
Result
Not Attempted Yet
In 1950, Richard was 4 times as old as Robert. In 1955, Richard was 3 times as old as Robert. In which year was Richard twice as old as Robert?
(A) 1960
(B) 1965
(C) 1970
(D) 1975
(E) 1980
(A) 1960
(B) 1965
(C) 1970
(D) 1975
(E) 1980
01 Dec 2015, 06:03
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In 1950,
Let Richard's age = Ri
Robert's age = Ro
Ri = 4*Ro -- 1
In 1955,
Ri + 5 = 3(Ro + 5)
=>Ri + 5 = 3Ro + 15
=>Ri = 3Ro + 10 -- 2
From equations 1 and 2 ,
4Ro = 3Ro + 10
=> Ro = 10
Ri = 40
Let the number of years needed from 1950 be x
40 + x = 2(10+x) = 20 + 2x
=> x = 20
Therefore , the year is 1970.
Answer C
Let Richard's age = Ri
Robert's age = Ro
Ri = 4*Ro -- 1
In 1955,
Ri + 5 = 3(Ro + 5)
=>Ri + 5 = 3Ro + 15
=>Ri = 3Ro + 10 -- 2
From equations 1 and 2 ,
4Ro = 3Ro + 10
=> Ro = 10
Ri = 40
Let the number of years needed from 1950 be x
40 + x = 2(10+x) = 20 + 2x
=> x = 20
Therefore , the year is 1970.
Answer C
Updated on: 07 Dec 2015, 07:20
Originally posted by Abhishek009 on 01 Dec 2015, 11:35.
Last edited by Abhishek009 on 07 Dec 2015, 07:20, edited 1 time in total.
Last edited by Abhishek009 on 07 Dec 2015, 07:20, edited 1 time in total.
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From the picture above we have 4r+5 = 3r + 15
Or, r = 10
Let the number of years be "x"
so, 40 + x = 2 ( 10 + x )
Or, 40 + x = 20 + 2x
Or, x = 20
So, After 20 years from 1950 ie 1970 Richard will be twice as old as Robert.
PS : Edited , all thanks to whitehalo
Or, r = 10
Quote:
Let the number of years be "x"
so, 40 + x = 2 ( 10 + x )
Or, 40 + x = 20 + 2x
Or, x = 20
So, After 20 years from 1950 ie 1970 Richard will be twice as old as Robert.
PS : Edited , all thanks to whitehalo
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