Quantitative Aptitude
Work and Time
Two pipes A and B filled a tank in 28 minutes and 42 minutes respectively. And another pipe C can empty the tank in 42 minutes. If all the three pipes are opened together at the same time, in how many minutes can the tank be filled?
A  42 minutes 
B  35 minutes 
C  30 minutes 
D  28 minutes 
E  None of These

Let work be 84 unit
When all pipe open together they fill (3 + 2 – 2 = 3 unit) in one hour
So, they fill 84 unit in
Work and Time Flashcard List
1) 
2) 
3) 
4) 
5) 
6) 
7) 
8) 
9) 
10) 
11) 
12) 
13) 
14) 
15) 
16) 
17) 
18) 
19) 
20) 
21) 
22) 
23) 
24) 
25) 
26) 
27) 
28) 
29) 
30) 