we know that
If E and F are independent, then P(E/F) = P(E) and P(F/E) = P(F)
P (E ∩ F) = P (E) P (F).
is equal to

on simplifying we get, 
Total number of beads =11
We have 6 beads are alike and next 5 beads are also alike , also since it is a necklace it can be observed from both the sides .
Therefore required number of ways=

Hence c is the root of the equation
The area enclosed by the curve is