Putra baked some mooncakes. There were 25% fewer pandan mooncakes than lotus paste mooncakes. He took 20 pandan mooncakes to give to his friends and baked another 13 lotus paste mooncakes. He packed the rest into boxes of 7 mooncakes each. If there were 5 lotus paste mooncakes in each box, how many pandan mooncakes did he bake at first ?
Solution:
This ratio problem has nothing in common, no internal transfer, total changed, each item changed. Nothing unchanged !
First we have to understand, there are two ratios as usual, before and after. The second ratio is the result of a process in between.
The trick to solve this issue is to equalise the After ratio and then multiply the remaining values by the same multiple used in multiplying the parts.
From here, it looks like an algebraic equation, that is
8u + 26 = 15u -100
or in model drawing can be represented as
So at first, Putra baked 3u or 54 pandan mooncakes.
Similar problem set will be the ratio of Tom's money to Sandra's money was 8:5 at first. After Tom spent $12 and Sandra received $24 from her mother, the ratio became 2:3. How much did Sandra have at first ?
ReplyDeleteAnswer: $30 (Problem Sum Type 19)