Two pipes A and B can fill a tank in 36 min. and 45 min. respectively. Another pipe C can empty the tank in 30 min. First A and B are opened. After 7 minutes, C is also opened. The tank filled up in:
A. 39 min.
B. 46 min
C. 40 min.
D. 45 min.
Answer: Option B
Solution (By Examveda Team)
Pipe A can fill empty tank in 36 min. Pipe A can fill the tank = $$\frac{{100}}{{36}}$$ = 2.77% per minute Pipe B can fill empty tank in 45 min. Pipe B can fill the tank = $$\frac{{100}}{{45}}$$ = 2.22% per min. A and B can together fill the tank = (2.77 + 2.22) ≈ 5% per minute So, A and B can fill the tank in 7 min. = 7 × 5 = 35% of the tank Rest tank to be filled = 100 - 35 = 65% C can empty the full tank in 30 min. C can empty the tank = $$\frac{{100}}{{30}}$$ = 3.33% per min. C is doing negative work i.e. emptying the tank A, B and C can together fill the tank, = 2.77% + 2.22% - 3.33% = 1.67% tank per minute So, A, B and C will take time to fill 65% empty tank, = $$\frac{{65}}{{1.67}}$$ = 39 min. (Approx)This Question Belongs to Arithmetic Ability >> Time And Work
46 full krne k liye lgega...39 empty k liye
I'm also getting 46 as the answer. Which one is the correct?
39+7=46 answer is right
A efficiency 5
B efficiency 4
c efficiency 6
work= efficiency à time
5Ã36=180
4Ã45=180
6Ã30=180
so
work=180
then A&B 7min work is
180-7Ã(5+4)
180-7Ã9
=117
then now c also open
so efficiency is 5+4-6=3
so tnk fll up in
=117÷3
=39 min
46 minutes total time 39 +7
and b 's work in 1 min 1/20andso a and b for 7 min 7/20,then remaining work is 13/20, after 7 min a+b+c 's work is 1/60 in 1 min and so for 13/20 th work done in 39 min and add before 7 min finally getting 46 min.