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A, B and C can complete a work in 10, 12 and 15 days respectively. A left the work 5 days before the work was completed and B left 2 days after A had left. Number of days required to complete the whole work is :
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8 2 3 -
6 2 3 - 7
- 6
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Correct Option: C
Let the whole work be completed in x days
| A’s 1 day’s work = | 10 |
| B’s 1 day’s work = | 12 |
| C’s 1 day’s work = | 15 |
According to the question,
A’s (x – 5) days’ work + B’s (x – 3) days’ work + C’s x days’ work = 1
| ⇒ | + | + | = 1 | |||
| 10 | 12 | 15 |
| ⇒ | = 1 | 60 |
⇒ 6x – 30 + 5x – 15 + 4x = 60
⇒ 15x – 45 = 60
⇒ 15x = 60 + 45 = 105
| ⇒ x = | = 7 days | 15 |
