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DS: Richard (m08q20)

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Re: DS: Richard (m08q20) [#permalink] New post 28 Aug 2013, 09:05
Expert's post
stevennu wrote:
Bunuel wrote:
tinki wrote:
sister now : s, richard now: s-3
st 1. 2(s-3-2) = s-2
St 2. s-2=2(s-3)

Could somebody help? whats wrong with my statements and logic?
thanks


If Richard is 3 years younger than his sister, how old will Richard be in 5 years?

Given: r=s-3. Question: r+5=s+2=?

(1) Two years ago Richard was twice as young as his sister --> 2*(s-3-2)=s-2 --> s=8 --> r+5=s+2=10. Sufficient.
(2) If Richard's sister were born 2 years earlier, she would now be twice as old as Richard --> if Richard's sister were born 2 years earlier she would now be s+2 years old not s-2, so s+2=2(s-3) --> s=8 --> r+5=s+2=10. Sufficient.

Answer: D.


Can you provide more detail in the steps of statement 1 and 2. I know you're using some shortcuts but I can't seem to follow.

Thanks,


(1) Two years ago Richard was r-2 years old and his sister was s-2 years old. We are told that then Richard was twice as young as his sister: 2*(r-2)=s-2, since given that r=s-3, then 2*(s-3-3)=s-2.

(2) If Richard's sister were born 2 years earlier, she would now be s+2 years old. We are told that in this case she would now be twice as old as Richard: s+2=2r --> s+2=2(s-3).

Hope it's clear.
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Re: DS: Richard (m08q20) [#permalink] New post 11 Aug 2014, 09:42
Hi Bunnel,
With all due respect, I find option I (1. Two years ago Richard was twice as young as his sister) outrightly wrong, not confusing. In effect, I think, this is not a valid question.
Lets take an example,
Person X has an age x and person Y has y.
Now, if its is given X is twice as old as Y; we mean x = 2y.
Can this be asked as, X is twice as young as Y. I think NO! There is no concept of being young.
We can say someone is 20 years old. It means his age in 20. But what do we infer when we say he/she is 20 year young?

Have you seen a single official question where young has been used in this sense? If yes, please do share.
Younger and Older are altogether different concept. They are relative difference and not multiples.

Thanks in Advance,
TR
Re: DS: Richard (m08q20)   [#permalink] 11 Aug 2014, 09:42
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