Question 849823
A nursery advertises that it has 16 elm trees for sale. Unknown to the nursery, 5 of the trees have already been infected with Dutch elm disease and will die within a year. (Hint: The buying of trees is done without replacement.) 

a)If a buyer purchases three trees, what is the probability that all three trees will be healthy? 

probability = {{{(matrix(2,1,11,3))(matrix(2,1,5,0))/((matrix(2,1,16,3)))}}} = {{{highlight(0.2946)}}}

b) What is the probability that at least one of the trees is infected?

Subtract the probability in letter "a" from 1, the result is
 1 - 0.2946 = {{{highlight(0.7054)}}}