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Question
Three spraying machines working together can finish painting a house in 60 minutes. How long will it take for 5 machines of the same capacity to do the same job?
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Solution
Let the time taken by 5 spraying machines to finish a painting job be x minutes.
| Number of machines | 3 | 5 |
| Time (in minutes) | 60 | x |
\[\text{ Since the number of spraying machines and the time taken by them to finish a painting job are in inverse variation, we have } : \]
\[3 \times 60 = 5 \times x\]
\[ \Rightarrow 180 = 5x\]
\[ \Rightarrow x = \frac{180}{5}\]
\[ = 36\]
\[\text{ Thus, the required time will be 36 minutes } .\]
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