In the recent PSLE maths paper, there was this question that was published in TODAY newspaper that stumped the students and made some cry.
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?
I asked Aaron if he knew the answer. He pondered a while and said the answer was 68. Then I asked his cousin Ben if he could do it. Ben said he could. So how hard could it be?
I tried to solve the question for two days but couldn’t do it. Mike couldn’t do it the model way too. I asked Aaron to show me. He said he did not know how, and knew the answer as it was published at the bottom of the article. That boy! I asked Andreas and Ivan. Both said they could only do so using algebra. I went back to Ben and asked him. He said he used trial and error method. I asked a calculus professor from US but he said it was too long winded for him. I asked another friend who forwarded the question to me, and he solved it using algebra, then told me that MOE also accepts this method.
I actually had one sleepless night trying to solve the question, and wondered who else I can ask to help me solve the question. I decided to put the question away and come back to it, but it was a niggling thought at the back of my mind
Tuesday morning while lying down on my bed at Raffles Hospital, after my colonscopy and stapler haemorrhoidectomy, I turned on the TV and 早安您好! was on and they were discussing this issue with a childcare operator and a mental maths teacher. And guess what, they provided me the answer step by step.
Immediately I thought of Law of Attraction at work.