Question: 
Two pipes A & B would be fill a tank in 20 & 30 minutes respectively. Both pipes being oppen, find when A must be turned off so that the tank may be just filled in 15 minutes.
After 10 minutes
After 20 minutes
After 15 minutes
None
After 10 minutes
Answer: 
After 10 minutes
Last Updated: 
08/11/2021 - 03:30