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?

Answer 1

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

\[\text{ Since the number of spraying machines and the time taken by them to finish a painting job are in inverse variation, we have } : \]
\[3 \times 60 = 5 \times x\]
\[ \Rightarrow 180 = 5x\]
\[ \Rightarrow x = \frac{180}{5}\]
\[ = 36\]
\[\text{ Thus, the required time will be 36 minutes }  .\]