Tap rates and a changing workforce

1. Two taps fill a tank together in \(12\) minutes. Tap A fills three times as fast as Tap B. Find Tap B’s time alone.
2. Fifteen workers, working \(8\) hours per day, plan to finish a project in \(6\) days. After two days, five workers leave. How many hours per day must the remaining workers work for the last four days?

For part (b), assume all workers maintain the same constant hourly work rate, with no efficiency loss when the workforce or daily hours change.