Suppose the food will last for D days at same rate .
250 men had provisions for 40 days.
( 250 - 50 ) men had provisions for D days.
Less men, More days ( Indirect Proportion )
we can write as :-
∴ 200 : 250 :: 40 : D ⇔ (200 × D ) =( 250 × 40 )
⇔ ( 250 × 40 ) /200 = 50
Therefore , 50 days is required answer .
