We start by determining the total amount of work done by the painting team. The work can be quantified in terms of member-minutes, where one member working for one minute contributes one unit of work.
Given that 12 members can complete the painting of a wall in 12 minutes, we can calculate the total work done in terms of member-minutes:
Now, we want to find out how long it would take for 18 members to finish the same wall, which still requires a total of 144 member-minutes of work.
Let
Since the total work required is the same (144 member-minutes), we set up the equation:
Next, we solve for
Calculating the right-hand side:
Thus, it would take 18 members 8 minutes to paint the wall. The final answer is: