32. If 17 labourers can dig a ditch 20 m long in 18 days, working 8 hours a day; how many more labourers should be engaged to dig a similar ditch 39 m long in 6 days, ech labourer working 9 hours a day?
[A] 34
[C] 68
[B] 51
[D] 85
Answer : B
Explanation :
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Let the total number of men to be engaged be x. |
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More length, More labourers (Direct Proportion) |
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Less days, More labourers (Indirect Proportion) |
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More hours per day, Less labourers (Indirect Proportion) |
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| Length | 26 : 39 | Days | 6 : 18 | Hours per day | 9 : 8 | |
| :: 17 : x |
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| (26 x 6 x 9 x x) = (39 x 18 x 8 x 17) |
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| x = | (39 x 18 x 8 x 17) | (26 x 6 x 9) | | = 68 | |
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| Number of more labourers = (68 - 17) = 51 |
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Title : Chain Rule Q32
Description : 32. If 17 labourers can dig a ditch 20 m long in 18 days, working 8 hours a day; how many more labourers should be engaged to dig a similar ...
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