Correct option is A
Given:
Fill pipe rate = fills tank in 21 min
211 tank/min
Empty pipe rate = empties tank in 24 min
−241 tank/min
Both start on an empty tank; find time to fill 41 tank.
Formula Used:
Time =RateWork.
Solution:
Net rate =211−241=1688−7=1681 tank/min.
Time to fill 41 tank =168141=4168=42 minutes.