30 men working 7 hrs a day can do a work in 18 days. In how many days will 21 men working 9 hrs a day do the same work?

Question

Question

This question was previously asked in

Chandigarh Police Constable Official Paper (Held On: 23 Jul, 2023)

Answer 1

Given:

Number of men (M₁) = 30

Hours per day (H₁) = 7

Number of days (D₁) = 18

For the second case:

Number of men (M₂) = 21

Hours per day (H₂) = 9

Number of days (D₂) = ?

Formula used:

Since the total work remains constant:

M₁ × H₁ × D₁ = M₂ × H₂ × D₂

Calculation:

30 × 7 × 18 = 21 × 9 × D₂

⇒ D₂ = (30 × 7 × 18) / (21 × 9)

⇒ D₂ = 20 days

∴ The correct answer is option (1).

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