The following question appeared in paper 2 of the June 2015 additional examination (actual question number 4.3):

Drug-testing kits are sometimes used in schools. The current drug test which uses blood or urine samples is considered to be too personal (invasive). A new drug test, the Saliva Drug Test (SDT), uses saliva and is considered to be less personal than the current test. It can be used to test for up to 9 different types of drugs.

The pictures below show the drug-testing instrument and the swab used to take a sample of saliva.

The tree diagram below shows the outcomes of the SDT after testing the saliva of the same person twice.

Study the tree diagram above to answer the following questions.

1. Give the probability (as a common fraction) of obtaining both …show more content…
Presently a certain school uses a different kind of drug test that has an accuracy rate of 97%. This school is considering using the SDT. The school counsellor commented that the difference between the accuracy rates of the two tests is negligible. Critique his comment by determining how many less inaccurate results will be obtained if the SDT is applied only once to a sample of 1 000 learners.

5.1 Conclusion
In this unit we looked at probability, how to calculate probability and how to determine probability in the case of compound events (where two or more events take place). Finally, the significance of knowledge of probability for our daily lives were discussed. We have seen that knowledge of probability can assist the man in the street to take responsible decisions when it comes to gambling and to interpret results of research or tests of which the outcome(s) relate to probability.

You are now finished with this content module regarding data handling and probability. Review all the outcomes of this module and ensure that you can answers questions related to all of it.

Glossary

Fatality death caused by an accident or by violence, or someone who has died in either of