Data Interpretation is one of the least liked sections of CAT by most students. The copious amount of calculation involved puts off even the most diligent of students. Again, this is one of those subjects where students can dramatically improve their scores by putting in some practice. But don’t just solve the entire set by force, put in some smart work. Learn the tricks of approximation and calculation given above and put them to use every time you solve a set. The crux of doing well in Data Interpretation is accurately solving in less time. Most of the students are able to understand what is asked and how to do it. The only difference between a high scorer and a low scorer is accuracy and speed. As most of the questions are interrelated (as in the data derived from one is used by another) these errors can get compounded during the exam. Make sure you spend enough time accurately solving those questions where the data derived will be used by the other questions. Use the techniques given above to improve you time, but be cautious of over approximating. Approximating 1729 to 1700 is very different from approximating 17 to 20.

Rate of Growth:

• Provided r the rate of growth for n years, we can approximate it as follows: By binomial theorem $$ (1+x)^{n} $$ = 1 + nx + $$\frac{n(n-1)}{2!}x^{2}$$ + $$\frac{n(n-1)(n-2)}{3!}x^{3}$$...
• If nx<10%, we can approximate this to 1+nx. Else, approximate to the third term.
• If we are given the value after n years of r rate of growth and asked for the earlier value. Here n will be negative in the formula given above
• Suppose p was the value in 2009 and after 2% growth for 3 years we get 100 in 2012. Hence $$ p $$ = $$\frac{100}{(1+2\%)^{3}}$$. We can approximate this to p=100(1-3*2%+((-3)(-4)/2!)*0.04%)=100(1-6%+6*0.04%)=94.24. The actual value is 94.232, which is very close to our answer.