1.  The distance between two cities A and B is 330 km. A train starts from A at 8 a.m and travels towards B at 60 km/hr. Another train starts from B at 9 a.m. and travels towards A at 75 km/hr. At what time do they meet ?
A. 10 a.m.
B. 10.30 a.m.
C. 11 a.m.
D. 11.30 a.m.

Answer: Option C

Explanation:

Suppose they meet x hrs after 8 a.m.
Then,

(Distance moved by first in x hrs) + [ Distance moved by second in ( x-1) hrs ]
  = 330
∴ 60x + 75 (x-1) = 330
=> x = 3
So, they meet at (8 + 3 )
i.e. 11 a.m.