A tap M can fill the tank of capacity 30 litres in 10 hours and anothe

1.	A tap M can fill the tank of capacity 30 litres in 10 hours and another tap N can fill the same tank in 15 hours. They opened simultaneously and tap M is closed after 2 hours. What was the time taken by tap N to fill the remaining part?1. 10 hours2. 20 hours3. 30 hours4. 15 hours5. None of these
Answer» Correct Answer - Option 1 : 10 hours Given: Total capacity of tank = 30 litres Time to fill the whole tank by tap M alone = 10 hours Time to fill the whole tank by tap N alone = 15 hours Calculation: Part of tank can be filled by tap M in 1 hour = 30/10 ⇒ 3 litres Part of tank can be filled by tap N in 1 hour = 30/15 ⇒ 2 litres Part of tank filled by tap M and tap N together in 1 hours = 3 + 2 ⇒ 5 litres Part of tank filled by tap M and tap N together in 2 hours = 2 × 5 ⇒ 10 litres Remaining part to be filled = 30 – 10 ⇒ 20 litres Time taken by tap N to fill the remaining 20 litres = 20/2 ⇒ 10 hours ∴ Time taken by tap N to fill the remaining part is 10 hours.

A tap M can fill the tank of capacity 30 litres in 10 hours and another tap N can fill the same tank in 15 hours. They opened simultaneously and tap M is closed after 2 hours. What was the time taken by tap N to fill the remaining part?1. 10 hours2. 20 hours3. 30 hours4. 15 hours5. None of these

Answer» Correct Answer - Option 1 : 10 hours

Given:

Total capacity of tank = 30 litres

Time to fill the whole tank by tap M alone = 10 hours

Time to fill the whole tank by tap N alone = 15 hours

Calculation:

Part of tank can be filled by tap M in 1 hour = 30/10

⇒ 3 litres

Part of tank can be filled by tap N in 1 hour = 30/15

⇒ 2 litres

Part of tank filled by tap M and tap N together in 1 hours = 3 + 2

⇒ 5 litres

Part of tank filled by tap M and tap N together in 2 hours = 2 × 5

⇒ 10 litres

Remaining part to be filled = 30 – 10

⇒ 20 litres

Time taken by tap N to fill the remaining 20 litres = 20/2

⇒ 10 hours

∴ Time taken by tap N to fill the remaining part is 10 hours.