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Question
It takes 60 days for 10 machines to dig a hole. Assuming that all machines work at the same speed, how long will it take 30 machines to dig the same hole?
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Solution
Let the number of days required be x.
| Number of machines | 10 | 30 |
| Number of days | 60 | x |
As the number of machines increases it takes less days to complete the work
∴ They are in inverse proportion, x1y1 = x2y2
10 × 60 = 30 × x
x = `(10 xx 60)/30`, x = 20
It takes 20 days to dig the hole
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