The mean anxiety score of a group was 25 before treatment and 19 after treatment.
Calculate the percentage decrease in the mean anxiety score. Show your working.
72 exam-style questions on Edexcel GCSE Psychology 11.2 Data analysis, covering 11.2.1 Arithmetic and numerical computation, 11.2.2 Descriptive statistics, 11.2.3 Tables, charts and graphs, 11.2.4 Primary and secondary data, and 11.2.5 Qualitative and quantitative data. Each one has a worked solution and a mark scheme showing where the marks go.