Correct Answer: 14 min. 40 sec.
Explanation:
Part filled in 4 minutes = 4 | ❨ | 1 | + | 1 | ❩ | = | 7 | . |
15 | 20 | 15 |
Remaining part = | ❨ | 1 - | 7 | ❩ | = | 8 | . |
15 | 15 |
Part filled by B in 1 minute = | 1 |
20 |
∴ | 1 | : | 8 | :: 1 : x |
20 | 15 |
x = | ❨ | 8 | x 1 x 20 | ❩ | = 10 | 2 | min = 10 min. 40 sec. |
15 | 3 |
∴ The tank will be full in (4 min. + 10 min. + 40 sec.) = 14 min. 40 sec.
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