2. Level 3 Certificate in Quantitative Problem Solving (MEI) and Level 3 Certificate in Quantitative Reasoning (MEI) Using frequencies in tree diagrams to calculate probabilities

3. Using frequencies to find probabilities Use frequencies with tree diagrams and other forms of representation to calculate or estimate probabilities, including conditional probabilities:

4. Using frequencies to find probabilities Use frequencies with tree diagrams and other forms of representation to calculate or estimate probabilities, including conditional probabilities:

5. Using frequencies to find probabilities Use frequencies with tree diagrams and other forms of representation to calculate or estimate probabilities, including conditional probabilities: Forecast ‘rain’ Forecast ‘no rain’ Rains 18321 Does not rain 279 201030

6. An image from an NHS Screening programme leaflet which uses expected frequencies to communicate the chances of different events following a mammogram: What is the chance that someone referred for more tests is diagnosed with cancer? Using frequencies to find probabilities Image from http://www.cancerscreening.nhs.uk/breastscreen/publications/ia-02.htmlhttp://www.cancerscreening.nhs.uk/breastscreen/publications/ia-02.html

7. Some balanced dice have probability 1/6 of coming up ‘4’. Out of 60 throws, how many ‘4’s would we expect to come up? Using frequencies to find probabilities

8. Some balanced dice have probability 1/6 of coming up ‘4’. Using frequencies to find probabilities Out of 60 throws, how many ‘4’s would we expect to come up?

9. 80% of the school students can roll their tongues. If I pick 1000 students at random, how many do you expect will NOT be able to roll their tongues? Using frequencies to find probabilities

10. 80% of the school students can roll their tongues. If I pick 1000 students at random, how many do you expect will NOT be able to roll their tongues? Using frequencies to find probabilities

11. In a typical school with 80 Year 10 students, 64 of them will have a profile on the social media site Face-ache. What is the probability that if we pick a Year 10 student at random, they will not have a profile? Using frequencies to find probabilities

12. In a typical school with 80 Year 10 students, 64 of them will have a profile on the social media site Face-ache. What is the probability that if we pick a Year 10 student at random, they will not have a profile? Using frequencies to find probabilities

13. A newspaper headline says that eating radishes doubles your chance of getting Smith’s Disease. 1% of people who don’t eat radishes get Smith’s Disease anyway. Using frequencies to find probabilities

14. A newspaper headline says that eating radishes doubles your chance of getting Smith’s Disease. 1% of people who don’t eat radishes get Smith’s Disease anyway. Using frequencies to find probabilities

15. A weather forecast is generally right. When it forecasts ‘rain’, 90% of the time it rains. When it forecasts ‘no rain’, 70% of the time it does not rain. Using frequencies to find probabilities In a typical September they forecast rain on two-thirds days and no rain on one-third of days.

16. A weather forecast is generally right. When it forecasts ‘rain’, 90% of the time it rains. When it forecasts ‘no rain’, 70% of the time it does not rain. Using frequencies to find probabilities In a typical September they forecast rain on two-thirds days and no rain on one-third of days.

17. OCR Resources: the small print OCR’s resources are provided to support the teaching of OCR specifications, but in no way constitute an endorsed teaching method that is required by the Board, and the decision to use them lies with the individual teacher. Whilst every effort is made to ensure the accuracy of the content, OCR cannot be held responsible for any errors or omissions within these resources. © OCR 2015 - This resource may be freely copied and distributed, as long as the OCR logo and this message remain intact and OCR is acknowledged as the originator of this work. OCR acknowledges the use of the following content: Slide 6 Page 9 of NHS breast screening information leaflet ‘NHS breast screening – Helping you decide’, © Crown copyright, taken from http://www.cancerscreening.nhs.uk/breastscreen/publications/ia-02.htmlhttp://www.cancerscreening.nhs.uk/breastscreen/publications/ia-02.html Thank you for using this OCR resource Other OCR resources are available at www.ocr.org.ukwww.ocr.org.uk We’d like to know your view on the resources we produce. By clicking on the ‘Like’ or ‘Dislike’ button you can help us to ensure that our resources work for you. When the email template pops up please add additional comments if you wish and then just click ‘Send’. Thank you.