题目

There are 5 yellow marbles ,1 purple marble ,3 green marbles ,and 3 red marbles in a bag .Once a marble is drawn ,it is replaced .Find the probability of each outcome.
1.A purple then a red marble 2.Tow green marbles in a row
3.a purple then a green marble

提问时间：2021-03-17

答案

total marbles:5+3+3+1=12
replaced 这指的是放回原处
1.明显,the p of 1 purple marble= 1/12
the p of 1 red marble= 3/12
they're independent.P=P1*P2=1/12 * 3/12 =1/48
2.the p of 1 GREEN marble= 3/12
the p of 1 GREEN marble= 3/12
they're independent.P=P1*P2=3/12 * 3/12 =1/16
3.the p of 1 purple marble= 1/12
the p of 1 GREEN marble= 3/12
they're independent event.P=P1*P2=1/12 * 3/12 =1/48
应该是这样吧·