IIT, IIM and CA examinations are meant different professionals. Now, let us consider the IIT first. This is a combined tests for the 23 different institutions where the admission - formality is finalised of the aspirants after considering their rankings in the final- list. There has been some modification in the examination - patterns. Unlike the previous years where there was a single test comprising Physics, Chemistry and Mathematics, the latest - system consists of two separate examinations - one for screening of the candidates and the other one is the advanced test for the real assessment of potentials of the aspirants for the final selection of any one of the institutes as indicated above.so, a thorough preparation for this test would make you a successful Engineer.
With respect to IIM, you have to clear the CAT test and only a high percentile can offer you a seat in the top management institutes. You have to make consistent effort to crack this management - test. If passed from a renowned institute, you would land into a glamorous job in the field of management.
Now lastly, CA test also known as Charted Accountant is a tough test evaluating your command over Accountancy, Commercial Mathematics and other tools in Mathematics such Differential - calculus, Integral- calculus, Vector etc. The result of the CA test does not exceed beyond 4 percent and so you can well estimate the toughness of the examination. A right guidance from a reputed institute and your total devotion would help you to crack this test.
Of course, there are provisions of reservations and for this you have to refer to book -lets provided by the different institutions.