This post will deal with Permutations and Combinations as a topic for preparation of JEE Advanced and JEE Mains.
Any student preparing for JEE Advanced and JEE Mains would instinctively know that Permutations and Combinations is one of the most important topics, for the number of questions that appear in the paper, and hence, the number of marks that it carries. This topic needs a very high level of understanding and rigorous practice to get the required finesse when it comes to the JEE Advanced level problems.
The trend from the previous years’ question papers shows that a sure-shot question will appear from this chapter in JEE Mains. As many as 3 questions were asked in JEE Advanced 2014, this recent upsurge in the number of questions making this chapter all the more important. A comprehension question which carries up to 12 marks appeared in 2011, 2012 and 2013. From the JEE Mains perspective, it is safe to assume that 1-2 questions from this topic will appear, as they have in all the previous years. So obviously this chapter is of utmost importance, and needs concentrated efforts to score maximum marks.
The Important topics and the nature of questions asked shall be discussed next.
The very high number of questions asked, directly gives way to the variety of questions that can be asked from this chapter. There are so many different types of questions, with particular solutions that can be framed, and hence rigorous practice is required.
The issue with Permutations and Combinations is that the solutions to these questions are generally complex. The basic idea for the solution needs to click in your mind right away, for them to be solved within a proper time frame and that only improves with the number of problems you solve in your preparation.
Few of the most common type of questions asked are the alphabet arrangement and dictionary type, where the rank of a certain word may be asked, the formation of integer type, the urn and ball type.
Another common type is where the elements in consideration are divided into pairs or sets, and subsets have to be developed. The problems may also appear in combination with the concepts of Binomial Theorem.
This is a topic where a student may commit a lot of “silly mistakes”, a lot of problems need to be solved to negate that.