Some question: In 1 kg mixture of sand and iron, 20% is iron. How much sand should be added so that the proportion of iron becomes 10%?
Options:
(A) 1 kg
(B) 200 gms
(C) 800 gms
(D) 1.8 kg
(E) None of these
Some stream of consciousness:
In 1 kg mixture quantity of iron = 200 gm
Let x gm sand should be added, then
10% of (1000 + x) = 200
\ x = 1000 gm = 1 kg The answer: (A).