Hi.. :)

Q3) Simply the expression to:

1/2 log(2)2 - 1/3 log(2)2 + 1/4 log(2)2 +....

[Read log(x)y as log of y with base x]

= 1/2 - 1/3 + 1/4 +...

= 1- log 2

[Use expression of log(1-x)]

Q4) Plot the graph of f(x)

Q9) Favourable cases = Total ways - unfavorable cases

Total ways = 6C3 * 4C2

Unfavorable cases = X & Y are included together = 5C2 * 3C1

Q14) nC2 = 91

:)