Tips & Tricks Given: P can complete a work in 60 days Q can complete the same work in 50 days Concept: Time is inversely proportional to efficiency. Calculation: Efficiency of P = 1/60 Efficiency of Q = 1/50 Efficiency ratio of P to Q = 1/60 : 1/50 ⇒ 50 : 60 ⇒ 5 : 6 ∴ The ratio of working efficiencies of P and Q is 5 : 6