A researcher examined anonymised medical records for women diagnosed with chlamydia. The records were grouped according to whether treatment began promptly after diagnosis.
The table shows how many women developed pelvic inflammatory disease during the following 12 months.
| Treatment after diagnosis | Number of women in the group | Number who developed pelvic inflammatory disease |
|---|---|---|
| Not treated promptly | 1500 | 90 |
| Treated promptly | 4500 | 45 |
Calculate the ratio of the percentages that developed pelvic inflammatory disease, using not treated promptly : treated promptly.
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.