(B) a Red and a Blue in Either Order

Tree Diagrams 1

1. I have a red pen, a blue pen and a green pen in my pocket. I pick one out at random, note its colour and replace it. I then draw another pen and note its colour.

Draw a tree diagram to show all possible outcomes. Use your diagram to calculate the probability of picking out

(a) 2 reds (b) A red and a blue in either order (c) Two pens the same colour (d) No green pens

2. In my pocket I have a 10p and two 50p pieces. I select a coin, replace it and draw again.

(a) two 50p coins (b) a total of 60p

3. A bag contains 3 red and 3 blue discs. A second bag contains 4 red and 2 blue discs. A disc is selected from the first bag and put into the second bag. A disc is then selected from this second bag and its colour noted.

Draw a tree diagram to show all possible outcomes. Use your diagram to calculate the probability of picking out from the second bag

(a) a red (b) A blue 4. A bag contains 12 balls: 3 red, 4 blue and 5 green. A ball is selected at random and replaced. A second ball is then selected.

(a) 2 red balls (b) Two balls of different colours (c) No green balls

5. Repeat question four but this time the first ball is not replaced before the second is picked.

6. A bag contains 4 black and 4 white balls. Two balls are selected without replacement.

(a) 2 black balls (b) At least 1 black ball

7. A bag contains 5 red and 3 yellow sweets. Two sweets are selected without replacement.

(a) a sweet of each colour (b) no yellow sweets