Hello warriors! In part 1, I’ve given some tips regarding making educated guesses if you are not aware of the question or want to give your luck a try. I’ll be giving tips to guess questions in mathematics correctly in this article.
1) Diagrams for Co-ordinate Geometry
Even if you don’t thoroughly understand a concept, drawing an approximate diagram according to the given scale can help you work out the radius, area, equations etc. easily. It might seem like a trivia but it really works in many cases.Â
2) You can delay practising Kinematics and Trigonometry
Despite what they say about these topics, you need a number of hours or perhaps days and even weeks to really master these two topics. And what do they yield – only 9 or 10 questions at the most out of 120. In the same amount of time, you can probably master several other topics and get your hands on 30-45 marks worth of questions.
So, I will suggest you to touch these topics only when you have extra time and have finished with the rest of your preparation.
Many argue are trigonometric methods can help you solve a number of questions. But what these main questions need are just the basics, which you will probably learn on your own between your school classes, homework, coaching classes, and assignments. For real expertise, you have to be really geeky and nerdy. So, keep your hands off it until you have mastered the rest.
3) Domain and Range of a Function
Questions related to finding domain of a function in NDA are usually asked as below:
If x = {0, 1, 2, 3, 4}, y = {2, 3, 4, 5} and x X, y   Y, then which of the following is a function in the given set –
(a) f1 = {(x,y) : y = x + 1}
(b) f2 = {(x,y) : x + y = >5}
(c) f3 = {(x,y) : y = x}
(d) None of these
In such questions, you do not have to solve the entire function.
Just put in the extreme values of the set in the function and see if they satisfy the answer. In this question, you can put 0 and 4 for x and 2 and 5 for y. You will be able to get the correct answer – (d) in this case.
4) Finding out n-terms in Mathematics
Perhaps the easiest questions in Maths, these either ask for the nth term or the sum or product of n-terms. The value of ‘n’ is mostly 1, 2 or at the most 3. Simply, put in these values and check whether they fit in.
If you have tried up to ‘3’ and you still do not have the answer, leave it alone. It is most likely to be a high-level question.
Here’s an example for you:
The sum of n natural numbers (1+2+3+….+n) is:
(a) n (n-1)/2
(b) n (n+1)/2
(c) n (n+2)/3
(d) (n+1) (n-1)
Sum of 1 as a natural number should be 1 too.
Put 1 as the value of n. Solving the equations you will get 0 for (a), 1 for (b), 1 for (c) and 0 for (d). Hence, we can rule out (a) and (d).
Now we put 2 as the value of n. Solving (b) equation, we get 3 as the answer while (c) equation dissolves into 8/3, which is not a natural number. Hence, the correct answer is (b).
5)Â Generalize the Question
These are the favorite questions of competitive examiners. They have complex orientation and you will have to find one of the variables.
Just assume that two or more of the arbitrary values are zero, one or some other easy value and check your options again.
Here’s an example:
For positive real values, it is given that m3x4 = n3y4 and m2< n2, then
(a)Â Â Â m3x2 > n3y2
(b)Â Â m3 < y4
(c)Â Â Â m3x2 < n3y2
(d)Â Â m3 > y4
Solving these will lead you to the hot soup of inequalities.
Hence, here’s an alternative. Assume some easy values for m, x, and n. Let’s say, m = 2, n = 3, and x = 3. You will get y as the fourth root of 24. Approximate it as the square root of 5 (since 5 is the square root of 25). Hence, it can be roughly calculated to be 2.2.
For such questions, approximating values is a good idea.
Put these values in the equation. Cancel out ‘3’ wherever possible and you will soon find the correct answer as (b).
In questions where you get random inclinations of a plane (alpha, beta or whatever), check what will happen if the inclination is zero/90. Put zero or 90 as the value of the plan and see which of the answers satisfy the condition.
You can apply the same logic to find Moment of Inertia about a random axis. Here’s an example:
Find Moment of Inertia (M.O.I) of a rod along an axis at theta degrees from its length passing through the centre:
(a) ML2sin2?/12
(b) ML2cos2?/12
(c) ML2sin?cos2?/12
(d)ML2sin2?cos?/12
We know that the M.O.I of a rod along its length is zero. So if ? = 0, M.O.I = 0 too. Assume ? = 0 and (a), (c) and (d) all turn out to be zero.
Also, the M.O.I of a rod perpendicular to its axis (for ?=90) = ML2/12. Using ? = 90, only (a) gives you that answer. (c) and (d) turn out to be zero. So, (a) is the correct answer.
Isn’t it simple?
6. Let the Mind Rule for Once!
I know what they say about always listening to your heart. But NDA is about testing your Intelligence and not your Intuition. So, let the mind decide which answer to tick and ask the Heart to just be the Motivator for the three hours when you are taking the test.
Pull out some sample NDA papers. Use these tricks to derive the answers to the questions in topics you have not studied yet and check your score!
I got an extra 44 marks in my NDA exam by following this very approach!
No matter what happens, never lose your confidence. Whether it is during preparation, during exam, or after the exams, keep your spirits high.
That reminds me to give you one more warning and one more tip:
Warning: Never carry a book or revision notes to the exam centre. It will just confuse you and stress you out in the last minute. Just carry your admit card and a pencil box/geometry box with the necessary stationery. And get at least six hours of sleep the night before the exam (Refer previous article on this).
Tip: When you feel your spirits floundering in despair, just plug in your earphones and listen to these songs; you can also find a list of some songs on an article on this site:
In English:
- Firework – Katy Perry
- Live like you’re dying – Kris Allen
- Lose Yourself- Eminem
- Remember the name – Fort Minor
- Someday – Flipsyde
In Hindi:
- Baar baar haan, bolo yaar haan – Lagaan
- Jo soche jo chahe woh kar ke dikha de – Do aur do Paanch
- Koi Kahe Rehte Rahe – Dil Chahta Hai
- Kya Karoon – Wake Up Sid
- Lakshya (the title song) – Lakshya
- Yeh Honsla Kaise Jhuke – Dor
Since you now have that josh, start preparing now. It’s hardly two months left! For the best book on NDA preparation, do read my review on Pathfinder for NDA & NA Exam in the next article. All the best for your NDA exams! I hope these tips will help you in cracking the exam. If you still have some queries or want to make anything clear, you can reach out to me by dropping me a message on fb through the link below. Good luck!
