If the probability of randomly choosing a county resident from a class of students is 65%, what is the probability of selecting exactly 7 county resident out of a random group of 10 students?
Combinations
p = .65
1-p = .35
P(7,10) = C(7,10) .65^7 * .35^3
C(7,10) = 10!/[7!*3!] =10*9*8/[3*2]
= 5*3*8
= 120
so
120 * .65^7 * .35^3 = .252