1. A box contains 2 red, 2 black and 3 white balls. One ball is drawn randomly from the box. After putting the ball back into the box, one ball is again drawn randomly. Find the probability that
(a) the two balls drawn are both red;
(b) the two balls drawn are of the same color;
(c) the two balls drawn are of the different color.
THZ! =]
Probability Problem
2008-05-27 12:24 am
回答 (2)
2008-05-27 12:32 am
✔ 最佳答案
a. P(2 red ball) = [2/(2+2+3) ]^2 = 4/49b. P(2 same colour)
= P(2 red ball or 2 black ball or 3 white ball)
= [2/(2+2+3) ]^2 + [2/(2+2+3) ]^2 + [3/(2+2+3) ]^2
= 17/49
c. P(two balls drawn are of the different color)
= 1- P(2 same colour)
= 32/49
2008-05-27 1:52 am
a. P(both red)=2/7*2/7=4/49
b. P(same colour)=P(both red)+P(both black)+P(both white)
=2/7*2/7+2/7*2/7+3/7*3/7
=17/49
c. P(different colour)=1-P(same colour)
=1-17/49
=32/49
b. P(same colour)=P(both red)+P(both black)+P(both white)
=2/7*2/7+2/7*2/7+3/7*3/7
=17/49
c. P(different colour)=1-P(same colour)
=1-17/49
=32/49
收錄日期: 2021-04-15 15:19:10
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