New Helicobacter infections were recorded in community surveys before and after a hygienic food-preparation programme.
| Survey period | People studied | New Helicobacter infections |
|---|---|---|
| before the programme | 900 | 72 |
| after the programme | 750 | 27 |
Calculate the percentage reduction in the proportion of people with a new Helicobacter infection from before the programme to after the programme.
Give your answer to two significant figures.
112 exam-style questions on Edexcel GCSE Biology 5.1 Health and communicable disease, covering 5.1.1 Communicable and non-communicable diseases, 5.1.2 Disease susceptibility interactions, 5.1.3 Pathogens as disease-causing organisms, 5.1.4 Common infections, 5.1.5 Spread and prevention of pathogens, 5.1.6 Lifecycle of a virus, and 5.1.7 Spread and prevention of STIs. Each one has a worked solution and a mark scheme showing where the marks go.