What is the probability that you will get at least 6 tails o

What is the probability that you will get at least 6 tails out of 9 times

P( X < 6) = P(X=5) + P(X=4) + P(X=3) + P(X=2) + P(X=1) + P(X=0)
= ( 9 5 ) * 0.5^5 * ( 1- 0.5 ) ^4 + ( 9 4 ) * 0.5^4 * ( 1- 0.5 ) ^5 + ( 9 3 ) * 0.5^3 * ( 1- 0.5 ) ^6 + ( 9 2 ) * 0.5^2 * ( 1- 0.5 ) ^7 + ( 9 1 ) * 0.5^1 * ( 1- 0.5 ) ^8 + ( 9 0 ) * 0.5^0 * ( 1- 0.5 ) ^9
= 0.7461

P( ATLEAST 6 TAILS) = P( X > = 6 ) = 1 - P( X < 6) = 0.2539