Mathematics for IGCSE & O level - Probability (Section 5 - No. 27)
There are 7 red and 3 yellow balls in a bag. Lee chooses a ball at random, notes its colour and replaces it. What is the probability that Lee chooses a red ball and then a yellow ball?
21/100
7/30
21/70
3/70
解释
P(red) = 7/10, P(yellow) = 3/10. So, P(red and yellow) = (7/10) * (3/10) = 21/100