Math Is Fun Forum

i) Geometric

X~Geo(1/3)
E(X) = 1/(1/3) = 3

VAR(X) = q/(p^2) = (2/3)/(1/9) = 6

ii) Binomial
X~B(7, 1/6)
E(X)=7(1/6) = 7/6

VAR(X) = 7(1/6)(5/6) = 35/36

iii) Looks like it'll be a Binomial but more info is needed such as the number of marks but P would be 1/2

iv) Same as iii