Correct Answer - Option 4 : 54

**Given:**

Number of days in which P and Q can complete the work = 36 days

Number of days in which P, Q, and R can complete the work = 24 days

**Concept used:**

Total work = Efficiency × Time period

**Calculation:**

Taking the L.C.M of 36 & 24

L.C.M of 36 & 24 = 72

One day work of P and Q = 72/36 = 2

One day work of P, Q, and R = 72/24 = 3

One day work of R = 3 – 2 = 1

Number of days R takes to complete 75% of work = (75/100) × (72/1) = 54 days

**∴ The number of days in which R can complete 75% of the work is 54 days.**