Question

Question #2ce41

Answer 1

`2/25, 9/100, 3/50` respectively

Explanation:

The bag contains in total `4 + 6 + 8 + 2 = 20` marbles.

The probabilities for each colour are as follows:

Blue: `4/20 = 1/5`

Red: `6/20 = 3/10`

Green: `8/20 = 2/5`

Yellow: `2/20 = 1/10`

For a probability of one thing followed by another, you simply multiply the two probabilities, so

`P("B then G") = 1/5 xx 2/5 = 2/25`

`P("R then R") = 3/10 xx 3/10= 9/100`

`P("Y then not G") = ?`

This last one is slightly trickier. The probability of something not happening is `1` minus the probability that it will happen, or

`P(barX) = 1-P(X)`

therefore

`P(barG) = 1-2/5 = 3/5`

so

`P("Y then not G") = 1/10 xx 3/5 = 3/50`