Let t be the number of hours needed for A and B to drain the tank.
1/5=part drained by A in 1 hr.
1/6=part drained by B in 1 hr.
1/t=part drained by both in 1 hr.
1/5+1/6=1/t, solve for t
Can you guys help me answer this question? It's been far too long since I've done ratios.
"Drain A will empty a tank in 5 hours. Drain B will empty the tank in 6 hours. How long will it take to empty the tank using both drains?"
"30 min : q min = 6 days : 2 weeks"
galactus has demonstrated what you should calculate. I'll add a few steps so it could be easier for you to understand:
1. contents of the tank: T
2. part of the content which is drained by A in 1 hour: 1/5*T
3. part of the content which is drained by B in 1 hour: 1/6*T
4. part of the content which is drained by A and by B together in 1 hour: 1/5*T + 1/6*T
5. Both pipes need t hours to drain the tank completly:
. simplify the LHS:
. Divide by T and then solve for t:
To be exact the time is: 2 h; 43 min; 38.18 s