From Goa to Bombay there are two roots; air, and sea. From Bombay to Delhi there are three routes; air, rail, and road. From Goa to Delhi via Bombay, how many kinds of routes are there?
we have to go from Goa to Delhi via Bombay.
Given: the number of ways from goa to Mumbai is air and sea
Therefore, the number of ways to go from Goa to Mumbai is 2C1
Given a number of ways from Mumbai to Delhi are air, rail, and road.
Therefore, the number of ways to go from Mumbai to Delhi is 3C1
Hence the number of ways to go from Goa to Delhi via Bombay is 2C1 × 3C1 = 2 × 3 = 6