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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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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 in Brief
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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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Chapter 10: Direct and Inverse Variations - Exercise 10.2 [Page 13]

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R.D. Sharma Mathematics [English] Class 8
Chapter 10 Direct and Inverse Variations
Exercise 10.2 | Q 10 | Page 13

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