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 By: rctw1989 (offline)  Friday, March 01 2013 @ 07:15 AM CST (Read 759 times)
rctw1989

Need some help for the following qn (model or algebra approach is ok)
8 yrs ago the ratio of x's age to Y's age was 8:1. Now the ratio is 10:3. How old will y be in 6 yrs' time. tks (answer is 18 yrs old)

Newbie

Registered: 12/31/12
Posts: 3

 By: echeewh (offline)  Friday, March 01 2013 @ 03:32 PM CST
echeewh

Hi there,

Following pls find my worked solution:

<8 years ago>
X : Y
8 : 1

<now>
X : Y
10 : 3

Since age difference between X and Y are constant (7 units in both instances), then we have ...

for Y,
3u - 1u --> 8 yrs
2u --> 8 yrs
1u --> 4 yrs

Hence, now Y's age is 3u --> 3 × 4 = 12 yrs

In 6 years time, Y's age is (12 + 6) = 18 yrs old

==================

Trust this helps.

Do let me know again if there's further clarification.

Cheers,
Edward

Active Member

Registered: 04/21/11
Posts: 627

 By: rctw1989 (offline)  Saturday, March 02 2013 @ 04:50 AM CST
rctw1989

hi edward

tks for your help. just today i used guess n check to solve it (multiplying the 2 respective ratios by 2, 3,4 ...

8 yrs ago now

8:1 10:3
16:2 20:6
24:3 30:9
32:4 40:12 ( check 32 +8 =40, and 4+8 =12, bingo) ans 12+6=18

wondering if there is a third way to solve, using model?

have a great weekend

Newbie

Registered: 12/31/12
Posts: 3

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