1, a volleyball is arranged in the order of 1 white 1 white 2 black 1 white 3 black 1 white 4 black ... make clear whether the ball 120 is black or white, which one is black or which one is white. Answer: the fifteenth white ball. Draw 120 balls without scoring. This problem can be used as a solution.

There are two cars, A and B, coming from opposite directions of A and B respectively. The first meeting place is 60 meters away from A, and the two cars immediately turn around when they reach a certain end of AB, and the third meeting place is 80 meters away from A, so find the distance between AB and B. Answer: AB is 1 10 meters away, and the second meeting place is 70 meters away from B, and this problem is also solved.

There are 20 cards in the box, blue 14, red 4 and green 2. Party A and Party B play games and draw cards at random, from which three cards are drawn. If there are only two colors of cards, even if Party A wins, how likely is it to win? Answer1119. Fill in the blanks?

Are these three questions enough? It's all my own. A pot of primary school students must be enough.