Three types of flour, S, T and U come in containers of 180 g, 240 g and 360 g respectively. Containers of S, T and U are mixed together in the ratio 3 : 5 : 7 to obtain 38.34 kg of an assortment of flour.

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

	S	T	U
Number	3 u	5 u	7 u
Value	180	240	360
Total value	540 u	1200 u	2520 u

(a)
Total mass of flour
= 540 u + 1200 u + 2520 u
= 4260 u

4260 u = 38340

1 u = 38340 ÷ 4260 = 9

Total number of containers of S and T used
= 3 u + 5 u
= 8 u
= 8 x 9
= 72 

(b)
Combined weight of all the flour in containers T and containers U
= 1200 u + 2520 u
= 3720 u

Difference between the combined weight of all the flour in containers T and containers U as compared to the flour in containers S
= 3720 u - 540 u
= 3180 u
= 3180 x 9
= 28620 g
= 28.62 kg 

Answer(s): (a) 72; (b) 28.62 kg