q1). There is only one combination that will give you the product of the form x^2 - by^2.

This is (x+y), (x-y).

Number of possible pair selections out of 4 = 4! / 2! 2! = 6.

So out of these 6 possible pairings only one is favorable hence the answer = 1/6.


q2). Just look at the venn diagram. It would suitable explain the situation to you. There is now ay you could have cetainly got the no. without considering both the statements.

q3). See We know the proportion of bars rashid handed out. The solution proceeds as follows:

stmt 1: choc + 1 = tof.

But you can never get the value of any variable from here.

stmt 2 : 2/3 choc = 3/5 tof.

=> 10c = 9tof.
this is just a ratio and hence this alone too can't give you the number.

But if u combine both the stmts the answer becomes evident.

Only one question per thread please ..