Discussion

Explanation:

Let time taken by Soham and Rohan to walk 50 kms be t and t + 2 hours respectively.

⇒ Soham's speed = 50/t
⇒ Rohan's speed = 50/(t + 2)

With double speed Rohan takes 1 hour less than Soham to walk 50 kms.

⇒ $\frac{50}{2\times \left({\displaystyle \frac{50}{\mathrm{t}+2}}\right)}$ = t - 1

⇒ 50 = $2\times \left(\frac{50}{\mathrm{t}+2}\right)\times (\mathrm{t}-1)$

⇒ $\frac{1}{2}$ = $\left(\frac{t-1}{\mathrm{t}+2}\right)$

⇒ t + 2 = 2(t - 1)

⇒ t = 4 hours.

Hence, option (a).

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