My son. perspiring profusely, came back empty handed after walking 400m in the sweltering heat.  "Dad, your $1.50 is not enough! My milo peng cost $1.80 now. " A teachable moment.  I hoped he learnt two things from this ordeal.  Inflation and the need to plan for things going wrong a.k.a margin of safety and ask for some additional coins in future. "Here is 30 cents! Go, my young padawan and bring back the elusive milo peng to quench your thirst. Get me the delectable bak chor mee, less chilli. Take another $3.50 for the mee. It was $3.50 last month." (adsbygoogle = window.adsbygoogle || []).push({}); He rushed out immediately. Guess he didn't learnt his lesson on the need for a margin of safety and inflation. He will learnt some day..for he must learn.
Weightage of basket (Figure 1) 
Source : Department of Statistics Singapore Breakdown on...