Tap 1 and tap 2 can independently fill an empty swimming pool in 30 min and 40 min, respectively. Similarly, Drain plugs D1 and D2 can
independently drain the same pool fully in 30 min and 20 min, respectively. When the pool is full with stale water, what is the minimum time
required to fill half of it with fresh water?
25
141/2
204/7
20
12
Answers
Answered by
0
Answer:
the elephant on the right hand side looks stronger than the one on the left hand side (rewrite the sentence in the positive degree)
Answered by
2
Answer:
evaluate efficiency of t1 and t2.
evaluate efficiency of D1 and D2.
evaluate overall efficiency.
t1 +t2 -d1 -d2
work done = efficiency * time taken
where work done is 1/2
answer = 20
Similar questions