Một hộp có 100 tấm thẻ như nhau ñược ghi các số từ 1 ñến 100, Rút ngẫu nhiên hai thẻ rồi ñặt theo thứ tự từ trái qua phải. Tính xác suất ñển

Afootball quarterback has two more chances to throw a touchdown before his team is forced to punt the ball. he misses the receiver on the first throw 25% of the time. when his first throw is incomplete, he misses the receiver on the second throw 15% of the time. what is the probability of not throwing the ball to a receiver on either throw?