- 130
- 70
- 100
- 91

Option 2 : 70

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NTPC Diploma Trainee 2020: Full Mock Test

12144

120 Questions
120 Marks
120 Mins

**Given:**

Rahul is 30% more efficient than Dolly, Dolly takes 21 days more than Rahul to complete a piece of work.

**Concept:**

Efficiency is inversely proportional to the time.

**Calculation:**

Ratio of efficiency of Rahul and Dolly = 130 ∶ 100

Ratio of time taken by Rahul and Dolly = 100 ∶ 130

Let Rahul takes 100x days, and Dolly takes 130x days to complete a piece of work.

Days taken by Dolly – Days taken by Rahul = 21

⇒ 130x – 100x = 21

⇒ 30x = 21

⇒ x = 21/30

⇒ x = 7/10

Days taken by Rahul = 100x

⇒ 100 × (7/10)

⇒ 70

**∴**** Rahul will take 70 days to complete the same work.**

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