Question

A car can finish a certain journey in 10 hours at the speed of 48 km/hr. By how much should its speed be increased so that it may take only 8 hours to cover the same distance?

Answer 1

Let the increased speed be x km/h.
 

Time (in h)	10	8
Speed (km/h)	48	x+48

\[\text{ Since speed and time taken are in inverse variation, we get: }  \]
\[10 \times 48 = 8\left( x + 48 \right)\]
\[ \Rightarrow 480 = 8x + 384\]
\[ \Rightarrow 8x = 480 - 384\]
\[ \Rightarrow 8x = 96\]
\[ = 12\]
\[\text { Thus, the speed should be increased by 12km/h } . \]