Points A and B are 200 km apart. A person starts from A at 10 a.m. at a speed of 10 km/h and goes towards B. Another person starts from B at 11 a.m. at a speed of 20 km/h and goes towards A. At what time will they meet?

Points A and B are 200 km apart.

Total distance between points A and B = 200 km

 As given in the question the first person started 1 hour before the second person. So at the speed of 10 km/h, he can cover 10 km in one hour.

At 11 a.m. both of them go toward each other. So the distance between them at 11 a.m. = 200-10 = 190 km

Time taken by both of them to meet with each other = $$\frac{distance\ remaining\ at\ 11\ a.m.}{relative\ speed}$$

= $$\frac{190}{10+20}$$

= $$\frac{190}{30}$$

= $$\frac{19}{3}$$

= $$6\frac{1}{3}$$ hours

time will they meet each other = 11 a.m. + $$6\frac{1}{3}$$ hours

= 11 a.m. + 6 hours 20 minutes [we know that 1 hour = 60 minutes]

= 5:20 p.m.