英文概率计算要过程和解答,可中可英Two balls are drawn in succession without replac_英语解答

英文概率计算要过程和解答,可中可英
Two balls are drawn in succession without replacement from a box
containing 4 red and 2 white balls. What is the probability of
drawing a red ball on the second draw?

人气：114 ℃　时间：2020-09-30 14:34:07

解答

第一轮r4/6---剩3r2w---第二轮r3/5
4/6*3*5=12/30
第一轮w2/6---剩4r1w---第二轮r4/5
2/6*4/5=8/30
12/30+8/30=2/3