Question

If arun had walked 1 km/h faster, he would have taken 10 minutes less to walk 2 kilometre. What is arun’s speed of walking?

Answer 1

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Answer 2

ANSWER:  

Speed of arun is 3 kmph.

SOLUTION:

Given, arun had walked 1 km/h faster, he would have taken 10 minutes less to walk 2 kilometre.  

We need to find what is arun speed of walking?

Let arun speed of walking be x kmph.

Then, time taken by arun to walk 2 km is $\frac{2}{x}$ hours

If he had walked 1 kmph faster:

$\text { Then, time taken is } \frac{2}{x} \text { hours }-10 \text { minutes }=\frac{2}{x} \text { hours }-\frac{10}{60} \text { hours }=\left(\frac{2}{x}-\frac{1}{6}\right) \text { hour. }$

And speed is (x + 1)

Then, distance walked = speed x time

$\begin{array}{l}{2=(x+1) \times\left(\frac{2}{x}-\frac{1}{6}\right)} \\\\ {2=x\left(\frac{2}{x}-\frac{1}{6}\right)+1\left(\frac{2}{x}-\frac{1}{6}\right)} \\\\ {2=2-\frac{x}{6}+\left(\frac{2}{x}-\frac{1}{6}\right)} \\\\ {\frac{x}{6}-\left(\frac{2}{x}-\frac{1}{6}\right)=2-2} \\\\ {x^{2}-12+x=0} \\\\ {(x+4)(x-3)=0} \\\\ {x=3 \text { or }-4}\end{array}$

Here, we can neglect -4,

Hence, speed of arun is 3 kmph.