SOLUTION: It takes 12 minutes to fill a bath when the cold water tap is turned on full. The hot water tap takes 20 minutes to fill the bath if it is turned on full. How long does it take to

Algebra ->  Rate-of-work-word-problems -> SOLUTION: It takes 12 minutes to fill a bath when the cold water tap is turned on full. The hot water tap takes 20 minutes to fill the bath if it is turned on full. How long does it take to       Log On


   



Question 955278: It takes 12 minutes to fill a bath when the cold water tap is turned on full. The hot water tap takes 20 minutes to fill the bath if it is turned on full. How long does it take to fill the bath if both taps are turned on full at the same time?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Add their rates of filling:
+1%2F12+%2B+1%2F20+=+1%2Ft+
where +t+ = time in minutes
Multiply both sides by +60t+
+5t+%2B+3t+=+60+
+8t+=+60+
+t+=+7.5+
It takes 7.5 min with both taps turned on