Class 11

Math

Co-ordinate Geometry

Straight Lines

$15$ buses operate between Hyderabad and Tirupathi.The number of ways can a man go to Tirupathi from Hyderabad by a bus and return by a different bus is

- $15$
- $150$
- $210$
- $225$

While return trip, in order to come with different bus, number of buses left $=14$.

Number of ways to choose $1$ bus for return trip $=$ $_{14}C_{1}$

So, the required number of ways for going and return $=$ $_{15}C_{1}×_{14}C_{1}=210$