| (A + B)'s 1 hour's work = |
❨ |
1 |
+ |
1 |
❩ |
= |
9 |
= |
3 |
. |
| 12 |
15 |
60 |
20 |
| (A + C)'s hour's work = |
❨ |
1 |
+ |
1 |
❩ |
= |
8 |
= |
2 |
. |
| 12 |
20 |
60 |
15 |
| Part filled in 2 hrs = |
❨ |
3 |
+ |
2 |
❩ |
= |
17 |
. |
| 20 |
15 |
60 |
| Part filled in 6 hrs = |
❨ |
3 x |
17 |
❩ |
= |
17 |
. |
| 60 |
20 |
| Remaining part = |
❨ |
1 - |
17 |
❩ |
= |
3 |
. |
| 20 |
20 |
| Now, it is the turn of A and B and |
3 |
part is filled by A and B in 1 hour. |
| 20 |
∴ Total time taken to fill the tank = (6 + 1) hrs = 7 hrs.
