Question

In a bag of plain M and M's Yellow 20% red 20% orange 10% blue 10% green 10% brown 30%

Three M and M's are chosen give the probabilities

1. none are red
2. The third one is the first one that is yellow.​

Answer 1

1) P(none are red) = 51.2%

2) P(third one is the first one that is yellow) = 12.8%

Explanation:

We are given;

P(Yellow) = 20% = 0.2

P(red) = 20% = 0.2

P(Orange) = 10% = 0.1

P(Blue) = 10% = 0.1

P(green) = 10% = 0.1

P(brown) = 30% = 0.3

1) Probability that one is not red is;

P(one not red) = 1 - P(red)

P(one not red) = 1 - 0.2

P(one not red) = 0.8

Since 3 are selected, we will apply multiplication rule for independent events to get;

P(none are red) = 0.8 × 0.8 × 0.8

P(none are red) = 0.512

P(none are red) = 51.2%

2) To find the probability, that the third one is the first one that is yellow, we will use multiplication rule for independent events to get;

P(third one is the first one that is yellow)

= (1 - P(Yellow)) × (1 - P(Yellow)) × P(Yellow)

P(third one is the first one that is yellow) = (1 - 0.2) × (1 - 0.2) × 0.2

P(third one is the first one that is yellow) = 0.128

P(third one is the first one that is yellow) = 12.8%