Betty’s Better Betting Maths Game

Probably the best probability game on the www. ! was set up by one of Professor Assessor’s exceptionally gifted students, Betty Better …

I bet that you guessed – Betty liked betting better than anything …

1. When Betty went fishing, she caught 1000 fish in her net … one third were cod. What are the chances of her, at random, picking a cod ?

2. When Betty played cards, what were the chances of her picking a joker ?

3. When Betty tossed a coin, what were the chances of it landing on heads ?

4. Betty opened a book with 150 pages, what are the chances that the page was after page 100 ?

5. Betty opened a packet of 50 smarties – 20% of them were red. What chance does she have of picking a red one at random ?

6. Betty picked 10 flowers from her garden. Two in ten of them were yellow. What are the chances of her picking a yellow one ?

7. Betty wrote a letter to her friend. When she posted it, there were 199 others in the postbox – what percentage of the letters were sent by Betty ?

8. Betty had an album of 500 photographs. Half of them had ben taken on her holidays, one quarter were taken of the town where she lived and the rest were of her family. Of she picked one photograph at random, what were the chances that it was a photograph of her family ?

9. Betty could answer only three – quarters of the 20 questions in her maths examinations. What were the chances that the examiner picked a wrong question when he went to mark it ?

10. Betty’s pencil case contained 50 pencils and 5 pens. If she picked one at random, what were the chances that it was a pen ?

© Jacqueline Richards 2008

Answers :

1. 1 : 3

2. 1 : 52

3. 1 : 2

4. 1 : 3

5. 2 : 5

6. 1 : 5

7. 0.5 %

8. 1 : 4

9. 5 : 20 = 1 : 4

10. 5 : 45 = 1 : 8

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