EduGoog

Arvind starts walking  at 2 p.m. with the speed of 5 km/hr from P to Q.
Gopal goes on cycle at 3 p.m. with 10 km/hr from P to Q.
At what time Gopal will cross Arvind ? 

Option:
A. 3.15 p.m.
B. 3.20 p.m.
C. 3.30 p.m.
D. 4.00 p.m.
Answer: D . 4.00 p.m.

Justification:

Suppose, Gopal will cross Arvind after hour of Gopal's start.
Now, distance covered by Arvind = $(5 + 5/t)$ km
and distance covered by Gopal = $10/t$ km
Thus, $5 + 5/t = 10/t$ or $5=5/t$ or t = 1 hr.
Hence, Gopal will overtake Arvind at (3 + 1) p.m. = 4 p.m. 

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