12 pumps of one type pump 300 litres of water when each is running for 18 hours per day. But a set of 16 pumps of other types pump 400 litres of water when each is running for 24 hours per day. How efficient are the former type of pumps than latter type?

We know,
M₁D₁T₁W₂ = M₂D₂T₂W₁ [Men = M; Days = D; Time/Hours = T; Work = W]

Let the former type be E times efficient.
So, 1 former type pump = E x latter type pumps
So 1F = E x L
∴ 12F x 18 hours x 400 = 16L x 24 hours x 300
∴ (12 x E x L) x 18 x 400 = 16 L x 24 x 300 ------------------> Put value of F i.e. 1F
E = 4/3 = these are many times more efficient.