- Thread starter
- #1
veronica1999
Member
- Jun 4, 2012
- 63
An "unfair" coin has a 2/3 probability of turning up heads. If this coin is tossed 50 times, what is the probability that the total number of heads is even?
I set up an equation but I am having trouble with the calculation.
50C0 X (2/3)^0 X (1/3)^50 + 50C2 X (2/3)^2 X (1/3)^48 +............ 50C50 (2/3)^50X(1/3)^0
I tried splitting it up thinking of the sigma notation.
(2/3)^0 + (2/3)^2 .....................+ (2/3)^50 = { 1- (4/9)^25} / (1- 4/9)
(1/3)^0 ......................... + (1/3)^50 = { 1- (1/9)^25}/ (1-1/9)
It doesn't seem to work...
I set up an equation but I am having trouble with the calculation.
50C0 X (2/3)^0 X (1/3)^50 + 50C2 X (2/3)^2 X (1/3)^48 +............ 50C50 (2/3)^50X(1/3)^0
I tried splitting it up thinking of the sigma notation.
(2/3)^0 + (2/3)^2 .....................+ (2/3)^50 = { 1- (4/9)^25} / (1- 4/9)
(1/3)^0 ......................... + (1/3)^50 = { 1- (1/9)^25}/ (1-1/9)
It doesn't seem to work...