A takes 3 hours more than B to walk "d" km. If A doubles his speed, then he can make it in 1 hour less than B. How much time (in hours) does A required to walk "d" km?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 8
Concept Used:
Distance = Speed × time
⇒ Time = Distance/speed
Explanation:
A takes 3 hours more than B to walk 'd' km.
If A doubles his speed, then he can make it in 1 hour less than B.
Let the speed of the A be a km/h and B be b km/h.
According to the question -
(d/a) - (d/b) = 3 ....(i)
Again, (d/b) - (d/2a) = 1 ...(ii)
By adding equation (i) and equation (ii), we get
⇒ d/2a = 4
⇒ d/a = 4 × 2 = 8
So, it will take 8 hours by A to cover the distance d.