A takes 2 hours more than B to walk d km, but if A doubles his speed, then he can make it in 1 hour less than B. How much times does B required for walking d km ?
A. $$\frac{d}{2}$$ hours
B. 3 hours
C. 4 hours
D. $$\frac{2d}{3}$$ hours
Answer: Option C
Solution (By Examveda Team)
Suppose B takes x hours to walk d kmThen, A takes (x + 2) hours to walk d km
A's speed = $$\left( {\frac{d}{{x + 2}}} \right)$$ km/hr and
B's speed = $$\left( {\frac{d}{{x}}} \right)$$ km/hr
A's new speed = $$\left( {\frac{2d}{{x + 2}}} \right)$$ km/hr
$$\eqalign{ & \therefore \frac{d}{{\left( {\frac{d}{x}} \right)}} - \frac{d}{{\left( {\frac{{2d}}{{x + 2}}} \right)}} = 1 \cr & \Leftrightarrow x - \left( {\frac{{x + 2}}{2}} \right) = 1 \cr & \Leftrightarrow x - 2 = 2 \cr & \Leftrightarrow x = 4 \text{ hours} \cr} $$
This Question Belongs to Arithmetic Ability >> Speed Time And Distance
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