Question

A can type 100 letters in 5 minutes. B and C typing together can type 50 letters in 2 minutes. If all of them are working together then they can type 90 letters in how many minutes?

1. 4 minutes
2. 3 minutes
3. 2 minutes
4. 5 minutes
5. None of these

Answer 1

Correct Answer - Option 3 : 2 minutes

Given:

A types 100 letters in 5 minutes.

B and C together can type 50 letters in 2 minutes.

Formula Used:

Work = Time × Efficiency 

Calculation:

A types 100 letters in 5 minutes. 

B and C typing together can type 50 letters in 2 minutes.

Efficiency of A = 100/5 = 20 letters/min

Efficiency of B and C = 50/2 = 25 letters/min

Combined efficiency of A, B and C = 20 + 25 = 45 letters/min

Time taken to type 90 letters by A, B and C together = 90/45 = 2 min

∴ Together they can type 90 letters in 2 minutes.