(Solved): Sponsors of a local charity decided to attract wealthy patrons to its $500--plate dinner by allowing ...

Sponsors of a local charity decided to attract wealthy patrons to its $500--plate dinner by allowing each patron to buy a set of 21 tickets for the gaming tables. The chance of winning a prize for each of the 20 plays is 50 - 50. If you bought 21 tickets, what is the chance of winning 16 or more prizes?