The times, in seconds, taken by 12 athletes to run 400 m are
45.2,46.9,46.1,46.2,45.4,45.1,47.8,45.4,45.5,46.1,46.4,45.745.2,46.9,46.1,46.2,45.4,45.1,47.8,45.4,45.5,46.1,46.4,45.745.2,46.9,46.1,46.2,45.4,45.1,47.8,45.4,45.5,46.1,46.4,45.7.
Find the mean.
Find the sample standard deviation.
Find the median and quartiles.
8 exam-style questions on OCR (MEI) A Level Maths 2.2.12 Variance and standard deviation. Each one has a worked solution and a mark scheme showing where the marks go.