Six different software packages are available to solve a lin

Six different software packages are available to solve a linear programming problem and have been ranked from 1 to 6 (best to worst). An engineering firm, unaware of the rankings, randomly selects, and then purchases, two of the packages. Let Y be the number of packages purchased that are not the top-ranked one. Give (a) the possible values of Y , (b) the PMF of Y.

Solution

possible values of Y=selecting that are not top ranked=⁴C₂ =6 ways

b)pmf=6/⁶C₂=6/5*3=2/5