In a barrack of soldiers there was stock of food for 190 days for 4000 soldiers. After 30 days 800 soldiers left the barrack. For how many days shall the left over food last for the remaining soldiers?
(a)175 days
(b)200 days
(c)225 days
(d)250 days
Answer
Answer (as printed): B
Explanation
Let the remaining food last for $x$ days. 4000 soldiers had provisions for 160 days. 3200 soldiers had provisions for $x$ days. Less men, More days (Indirect Proportion). $\therefore 3200:4000::160:x \Leftrightarrow 3200x = 4000 \times 160 \Leftrightarrow x = \frac{4000 \times 160}{3200} = 200$.
Explanation as extracted from the printed page; notation may be imperfect.