Smarter Preparation for CAT- Tip No.1

I had separate conversations with a couple of CAT aspirants the other day. What I’ve come to realize over time is that the things they tell me and the things I say in return have started falling into predictable patterns. One can deduce that many of the problems faced by aspirants in preparing correctly and testing well are very similar. I’ll be writing about some of these issues, and how to overcome them, in this blog.

Both of these CAT aspirants mentioned preparing by themselves last year using study material that was handed down to them. And both ended up with percentiles which, while being decent in terms of the number of aspirants that they’d outperformed in the exam, were useless for getting any good B-school calls. If you have been in this situation, or know friends who have, here’s why.

The trade-off

Consider the simple example of comparing bubble sort and insertion sort algorithms. The bubble sort is the smallest piece of code you could write to perform sorting on an array. It’s also probably the easiest algorithm to explain. The insertion sort, on the other hand, is a longer piece of code and would take longer to explain to someone else. But we know that as far as execution time is concerned, the insertion sort takes a lot less. Check out this animation.

Basically, there’s a trade-off between ease of understanding and efficiency of execution. This is actually something you’ll encounter over and over again when you are preparing for CAT. There’s always a better and more efficient way of doing things which might not be immediately obvious. In fact, it might take a lot longer to figure out an efficient solution as opposed to the conventional way of solving it. Invariably, it also requires more effort to explain it, say, through a recorded video lesson or a textbook – which is why you’ll rarely see the most efficient way of solving a question in a text solution.

This is the most important tip for preparing for a management entrance exam, especially for people planning to prepare by themselves. Please, please don’t be satisfied with just getting the answer when you’re learning/ practicing. Spend some time analyzing your solutions to see what you are doing inefficiently.

Here are a couple of examples from Quant. Keep in mind that these are not CAT level questions, just examples to demonstrate what I mean.

Ex 1: If a man walks at 10 km/h, he reaches 15 minutes late to his office. If he walks at 15 km/h, he reaches 10 minutes early. Find the distance from his home to his office.

A traditional solution would look like this. Let the duration of the journey, when he reaches just in time, be t. Therefore, in case 1, he takes 15 minutes more than t, and in case 2, he takes 10 minutes less. Equating distances,

10 (t+\frac{15}{60})=15(t-\frac{10}{60})

which gives t = 1 hour

Putting it back in either side, distance = 12.5km

Here’s an alternative approach. (This might seem more tedious because it takes longer to read or understand, but once you become used to thinking like this, you’ll find that this is faster.)

  • The speeds are in the ratio 2:3, so the times should be in the ratio 3:2. (Inverse proportionality)
  • Also, since one is 15 minutes late and the other is 10 minutes early, we’re talking about a 25 minute difference.
  • Two numbers, in the ratio 3:2 and differing by 25, are 75 and 50.
  • 75 minutes \times 10km/h gives 12.5km.

The advantage is that the second approach lends itself well to paperless solving. This is because we can mentally manipulate statements with quantities better than long equations, especially ones that contain fractions. Let’s look at another one.

Ex 2: A farm has only ducks and bulls. If it is known that there are 80 heads and 300 legs, how many ducks are there?

The traditional approach is to assume variables d and b for the number of ducks and bulls respectively.
This gives  d + b = 80
And          2d + 4b = 300
Solving,    d = 10

This approach using simultaneous equations is easy enough to understand, but again, it constrains us to paper. Here’s an alternative:

  • Had all 80 animals been bulls, we would have had 320 legs.
  • If you replace one bull with a duck, the number of heads will remain the same, but the number of legs will reduce by two.
  • We need to reduce the number of legs by 20, so we need 10 replacements.
  • Hence, there are 10 ducks.

These are just two examples of the kind of alternative thought process you’ll require to solve a section in the time allotted. Back in school, we had around 5 minutes per question – now we have about 2. Around 75-80 percentile is probably manageable in CAT, if you solve the same way you did in school. But why spend all that time preparing for an 80? Why not just not write at all? For this whole exercise to be worthwhile at the end of the year, you really need to sit down and spend that extra time during preparation, to find the kinds of efficient approaches that will make your score matter.

To know more, attend a free workshop at ACME, PMG on February 24, 25.

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