Correct Answer - Option 4 : 2 pm
Given∶
Distance between Dehradun and Lucknow = 570 km
Speed of Chotu = 70 km/hr at 8 am towards Lucknow
Speed of Motu = 30 km/hr at 9 am towards Dehradun
Formula Used∶
When 2 bodies are moving with their speeds of x km/hr and y km/hr in the opposite direction, then their relative speed = (x + y) km/hr
And, Time = Distance/Speed
Calculation∶
Distance between Dehradun and Lucknow is 570 km.
Chotu leaving from Dehradun leaves an hour early than Motu who leaves from Lucknow.
So, Distance covered by Chotu leaving from Dehradun = 70 km/hr × 1 hr = 70 km
Distance left = 570 -70 = 500 km
Now, Motu from Lucknow also moving and both are moving towards each other.
So, Relative speed = 70 + 30 = 100 km/hr
∴ time required by them to meet = 500/100 = 5 hours
∴ Thus, they both meet at 5 hours after 9 am, i.e. 2pm.