Question

The ratio of zinc and copper in an alloy is 7:9. If the weight of copper in that alloy is 12.6kg .Find the weight of zinc.

Answer 1

zinc : copper = 7:9
zinc/11.7 = 7/9
zinc = 11.7(7/9) = 9.1 kg

Answer 2

zinc : copper = 7 : 9 : : x : 12.6

⇒7/9 =x/12.6

by cross multiplication,

⇒ 7*12.6=9*x

⇒88.2 = 9x

⇒88.2/9 = x

⇒ 9.8= x