Question 9
Example 1. Two pipes $A$ and $B$ can fill a tank in 20 minutes and 30 minutes respectively.
a) If both pipes are opened simultaneously, then find the time taken to fill the tank.
b) If pipe $A$ is opened first, after 10 minutes pipe $B$ is also opened. Find the total time taken to fill the whole tank.
c) If pipe $A$ is opened for 4 minutes and closed. Find the time taken by $B$ alone to fill remaining part of the tank.
**Editorial input convention:** Enter the three times in minutes, in a–c order, separated by commas.
**Editorial input note:** Use no spaces before or after commas.
a) If both pipes are opened simultaneously, then find the time taken to fill the tank.
b) If pipe $A$ is opened first, after 10 minutes pipe $B$ is also opened. Find the total time taken to fill the whole tank.
c) If pipe $A$ is opened for 4 minutes and closed. Find the time taken by $B$ alone to fill remaining part of the tank.
**Editorial input convention:** Enter the three times in minutes, in a–c order, separated by commas.
**Editorial input note:** Use no spaces before or after commas.