1. Take three balls. * * There are 6C3=20 ways to take it (6C3 means the combination number of six taking three). One for each of the three colors, * * 1 * 2 * 3 = 6 methods. So the probability is 6/20=0.3. There are only two ways to get two red balls (red, yellow, red and white), so 3c2 * (2c1+1) = 3 * (2+1) = 9, and the probability is 9/20.

2.P(A∪B)= P(A)+P(B)-P(AB)= P(A)+P(B)-P(A)P(B)= 1/4+ 1/5- 1/20

3. I just shot 3 times, but missed 7 times. The probability is 10c3 * 0.7 3 * 0.3 7 (x y stands for the y power of x).

Most likely 7 shots.

4 and 5 are too much trouble.

6.

-2 -4 -3 -2 - 1

p 1/6 1/3 1/6 1/3

* + 1 6 3 1

P 1/6 2/3