Data Interpretation is one of the key topics to be asked in GRE, CAT, Bank Exams, Placement Exams etc.,
Data is provided in the forms of charts (bar graph, pie-chart, column chart etc.,) and questions are based on them. It is easy but time consuming. One needs to interpret data correctly and also be fast in calculation.
There are generally 2 DI sets in bank exams (CAT, SBI and IBPS PO) having 5 questions each. These questions are relatively easy and doesn't require remembering formulae.
When graphs are given, there are multiple entities involved. You should not get confused (sometimes it is done in rush to complete the question)
Ex. Wheat production of 3 states - Goa, Sikkim and Kerala in 5 consecutive years 2008, 2009, 2010, 2011, 2012 is given. This is followed by a question - Find the ratio of production of wheat in Goa in 2009 to Sikkim in 2012.
The question is simple but there can be three probable mistakes
Ratio of Goa to Sikkim in the same year
Ratio of Goa in 2009 and 2010
And the most likely, ratio of Goa in 2012 to Sikkim in 2009
One should avoid all the above mentioned mistakes by being alert and not being in hurry. Remember, doing fast doesn't mean doing in a state of panic. You don't get marks for "knowing and not doing correct".
Questions are generally based on these three topics and one should have enough practice to solve them in the fastest way possible (You may use Speed Mathematics, Vedic Mathematics, trachtenberg or any other method that suits you).
In such questions, the choices of answers are very close and there is high probability of one attempting the wrong answer, if not done carefully.
One should avoid use of pen and paper as much as possible. Mental maths should be practised.
Ex. 54+72 = 50+70 and 4+2 = 126. This way if you bring your digits close to 10, you can do two-digit calculations fast.
This can be done by increasing or decreasing the number to the closest ten or hundred.
100% = 360 Degree. When Pie charts are available, remember to convert degree into percentage and vice-versa.
Performing well in DI requires steady mind and practice. You should start taxing your brain by doing mental maths even for day-to-day affairs, like adding grocery bills etc. Also, Avoid using calculators at all cost, wherever possible.