Friday, 23 October 2009

PSLE Math

As usual, there is furore over the PSLE Math paper AGAIN... apparently, some of the top students "broke down" after the paper. Parents complained that the were too difficult. One such question is:

"Jim bought some chocolates and gave half of it to Ken. Ken bought some sweets and gave half of it to Jim. Jim ate 12 sweets and Ken ate 18 chocolates. The ratio of Jim’s sweets to chocolates became 1:7 and the ratio of Ken’s sweets to chocolates became 1:4. How many sweets did Ken buy?"

Chris and I agree it IS SUPER CONVOLUTED for P6 kiddos. i bet even some of our JC kids will be stumped hahaha... seriously, BOTH chris and i don't know how to solve this WITHOUT using algebra... i'd do it this way:

let the number of sweets ken bought be s and the number of choc jim bought be c.

7 x (no. of jim's sweets left) = no. of jim's choc left => 7(0.5s - 12) = 0.5c ---- (1)
4 x (no. of ken's sweets left) = no. of ken's choc left => 4(0.5s) = 0.5c - 18 ----(2)

Solving (1) and (2) gives s = 68 (don't need to calculate c la...)

So, Ken bought 68 sweets.

sheesh... i can imagine if we have a kid... there'll be such a conversation...

kid: daddy, mummy, how to do this math question...?
us: this? that's easy... let x be.... let y be... form two equations... two equations, two variables, solve!
kid: but teacher says cannot use algebra...
us: er... then we don't know...
kid: your Maths so lousy one ah?
chris: It's not that our Maths is lousy... you should learn algebra.
kid: that time i used teacher marked me wrong...
chris: tell your teacher your mummy wants to talk to her!
me: O.O||| why mummy???

LOL

read the report here