These are the answers I have got. Please cross check and post if any of you get different answers. Also please explain the unanswered questions.
1. D, for continuous f(x) = lim, but info on limit is given and not on the value of function at x=3, so D
12. D, Since, uniform distribution fu. then P.M.F. = 1/10
15. C, just add xf(x) for x=1,2,3,4,5
I am getting D for 8, A for 10, B for 18 and can't solve 19,21,22,23,24.
For 9, from the revenue function you can find out the value of x when MR is 20. R=PQ so if you divide the revenue function by Q, you get the demand function. Using demand function find out the price and then elasticity.
@dhruv, thanks for 1, 12 and 15. 8 is d. My mistake.
For 10, i think it should be b because if the price consumption curve is parallel to x axis, this means that the points of utility maximisation (where indifference curves touch the budget lines) are in a straight line parallel to the x axis. This means that with the change in price, value of x is changing but value of y remains same. Hence, y has zero elasticity.
For 18, govt spending is a component of AD. Hence it will shift if there is a change in govt spending. I think it should be a.
I am not sure abt 24. Let's wait for other's point of view.