question_answer 18)

A car takes 2 hours to reach a destination by travelling at the speed of 60 km/h. How long will it take when the car travels at the speed of 80 km/h?

Answer:

                Let it take \[x\] hours. We have the following table.     

Speed (in km/h)	60	80
Number of hours	2	\[x\]

Lesser the speed, more the number of hours to reach the destination. So, this is a case of inverse proportion. Hence,       \[60\times 2=80\times x\] \[\Rightarrow \]               \[x=\frac{60\times 2}{80}\] \[\Rightarrow \]               \[x=\frac{3}{2}=1\frac{1}{2}\] Thus, \[1\frac{1}{2}\] hours would be taken.