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