Question

One hundred tickets, numbered 1, 2, 3, …, 100, are sold to 100 people for a drawing. Four different prizes are awarded, including a grand prize (a trip to Tahiti). How many ways are there to award the prizes if a) the person holding ticket 47 wins one of the prizes? b) the people holding tickets 19 and 47 both win prizes?

Answer 1

Solution :

It is given that four different prizes were awarded. So,

a). 4 ways for person 47 to win a prize

     99 ways to give out the 2nd prize

     98 ways to give the 3rd prize

      97 ways to give the last prize

     ∴  P(99,3) = 99 x 98 x 97

b). 1 way to give person 47 their prize

    1 way to give person 19 their prize

    98 ways to give out the 3rd prize

    97 ways to give out the last prize

    So, P(98,2) = 98 x 97