Venn Diagrams, Tree Diagrams and Probability

A box contains 3 brand A batteries and 7 brand B batteries. 30% of brand A batteries are faulty and 40% of brand B batteries are faulty. A battery is selected at random and then checked to see if it is faulty. What is the probability that a faulty brand B battery is selected?

• 0.28

• 1/4

• 0.42

• 0.21

A box contains 3 brand A batteries and 7 brand B batteries. 30% of brand A batteries are faulty and 40% of brand B batteries are faulty. A battery is selected at random and then checked to see if it is faulty. What is the probability that a not faulty brand A battery is selected?

• 0.21

• 0.09

• 0.28

• 0.25

James starts to draw a diagram for rolling two dice and recording whether a 6 is rolled or not. What is the probability of rolling no sixes?

• 25/36

• 10/12

• 2/12

• 2/36

A bag contains 3 lemons and 2 limes. A piece of fruit is taken from the bag and not put back. Then a second piece is taken. What is the probability of taking exactly 1 lemon?

• 12/20

• 6/20

• 2/20

• 18/20

In a box are 3 red pens, 4 black pens and 2 green pens. You pick a pen at random and then put it back. Your friend then picks a pen. What is the probability you both pick red?

• 1/9

• 2/9

• 6/9

• 4/9

In a box are 3 red pens, 4 black pens and 2 green pens. You pick a pen at random without putting it back. Your friend then picks a pen. What is the probability you both pick the same colour?

• 20/72

• 12/81

• 23/81

• 15/72

The probability of rain tomorrow is 1/4. If it does rain, the probability of school being closed is 2/5. If it does not rain, the probability of school being closed is 1/20. What is the probability that school is closed?

• 11/80

• 17/80

• 9/80

• 15/80

How many senior boys play football and wrestle?

• 9
• 12
• 18
• 39

How many senior boys play football but do not wrestle?

• 9
• 12
• 18
• 104

How many students do not snowboard?

• 21
• 22
• 28
• 29