Question #0c571

1 Answer
Oct 3, 2017

# 21/32.#

Explanation:

#"The Reqd. Prob="P(X>=3),#

#=1-P(X<3),#

#=1-{P(X=0)+P(X=1)+P(X=2)},#

Recall that, for a Binomial Random Variable X, with parameters

#p=50%=1/2, and, n=6," giving "q=1-p=1/2,#

#P(X=x)=""_nC_xp^x*q^(n-x)," where, "x=0,1,2,...,n.#

#:. P(X=x)=""_6C_x(1/2)^x(1/2)^(6-x)=""_6C_x(1/2)^6, i.e., #

# P(X=x)=(""_6C_x)/64," where, "x=0,1,2,...,6.#

#:." The Reqd. Prob.="1-1/64{""_6C_0+""_6C_1+""_6C_2},#

#=1-1/64{1+6+15}=1-11/32=21/32.#

Enjoy Maths.!