Answer:
a) 2.60x10^-7
b) 5.31x10^-5
c) 2.19x10^-3
Step-by-step explanation:
X=number of hits
The probability is the number of desired outcomes divided by the total number of all outcomes.
Then
a) P(X=6)=P({1, 1, 1, 1, 1, 1})=6/40*5/39*4/38*3/37*2/36*1/35=2.60x10^-7
b) P(X=5)=P({0, 1, 1, 1, 1, 1})+P({1, 0, 1, 1, 1, 1})+...+P({1, 1, 1, 1, 1, 0}), every one of these have the same probability
P(X=5)=6P({1, 1, 1, 1, 1, 0})=6*(6/40*5/39*4/38*3/37*2/36*34/35)=5.31x10^-5
c) P(X=4)=P({0, 0, 1, 1, 1, 1})+...+P({1, 1, 1, 1, 0, 0}) every one of these have the same probability.