This question was previously asked in

DSSSB PRT General Section Official Paper - 15 Nov 2019 Shift 1

Option 1 : 21 days

General Awareness Sectional Test 1

10072

40 Questions
40 Marks
15 Mins

**Given:**

Vivek alone can complete the work in 42 days

Mohit alone can complete the work in 56 days

**Concept:**

Work = Time × Efficiency

**Calculation:**

⇒ The efficiency of Vivek = 1/42

⇒ The efficiency of Mohit = 1/56

⇒ !n 12 day both can complete the work = 12 × (1/42 + 1/56) = 12 × (4 + 3)/(24 × 7) = (12 × 7)/(24 × 7) = 1/2

⇒ The remaining work = 1 - 1/2 = 1/2

⇒ The remaining work will be completed by Vivek = (1/2) ÷ (1/42) = 42/2 = 21 days

**∴ The required result will be 21 days.**