P5 Math: Flour and Sugar (A g a i n)

 

Sakinah bought an equal amount of flour and sugar. She paid a total amount of $83.20. How many kilograms of flour did she buy?

Solution:

For Primary school student, the answer should come in a whole units as shown in the picture (e.g bags, sacks, ...) and not partial. It means mass of flour would be: 500, 1000, 1500, ... 10000 g, and mass of sugar would be: 1.2, 2.4, 3.6, ... 12 kg.

Find the common multiple of the two items.
Flour: 500, 1000, 1500, ... 5500, 6000
Sugar: 1.2, 2.4, 3.6, ... 4.8, 6.0

The first common multiple is 6000 g or 6 kg. It is the first set of common multiple, when amount (the mass) of flour and sugar is equal.

Price of 6000 g of flour = 12 x $1.8 = $21.6.
Price of 6 kg of sugar = 5 x $4 = $20. 
Total both = $41.6.

However, Sakinah paid $83.20, it means she bought more than one set. 

$83.20 / $41.60 = 2 --> it means two sets:

• Flour: 2 x 6000 g = 12000 g
• Sugar: 2 x 6 kg = 12 kg

So, she bought 12000 g or 12 kg of flour as the answer.