Practice UPSC CSAT previous year questions from 2011–2026 classified underCounting / Combinatorics. Review the original question, four options, correct answer and explanation for every PYQ.
2 questions • 2011–2026
There are four routes to travel from city A to city B and six routes from city B to city C. How many routes are possible to travel from the city A to city C?
Each A→B route can be paired with each B→C route. Therefore 4×6 = 24.
Study the following figure. A person goes from A to B always moving to the right or downwards along the lines. How many different routes can he adopt?
The path requires two moves in one direction and two in the other, so the number of distinct arrangements is 4!/(2!2!) = 6.
Attempt questions one by one with UPSC-style marking and immediate explanations.