Three types of rice flour, R, S and T come in containers of 180 g, 360 g and 540 g respectively. Containers of R, S and T are mixed together in the ratio 1 : 4 : 7 to obtain 32.4 kg of an assortment of rice flour.

1. How many containers of R and S are used altogether?
2. Find the difference between the combined weight of all the rice flour in containers S and containers T as compared to the rice flour in containers R. Express the weight in kilograms.

	R	S	T
Number	1 u	4 u	7 u
Value	180	360	540
Total value	180 u	1440 u	3780 u

(a)
Total mass of rice flour
= 180 u + 1440 u + 3780 u
= 5400 u

5400 u = 32400

1 u = 32400 ÷ 5400 = 6

Total number of containers of R and S used
= 1 u + 4 u
= 5 u
= 5 x 6
= 30 

(b)
Combined weight of all the rice flour in containers S and containers T
= 1440 u + 3780 u
= 5220 u

Difference between the combined weight of all the rice flour in containers S and containers T as compared to the rice flour in containers R
= 5220 u - 180 u
= 5040 u
= 5040 x 6
= 30240 g
= 30.24 kg 

Answer(s): (a) 30; (b) 30.24 kg