A random sample of 12 measurements has mean 15 and Sxx=132S_{xx}=132Sxx=132.
Calculate the descriptive variance of the 12 recorded measurements.
Calculate the unbiased estimate of the population variance.
Explain which value should be used to describe only the observed measurements and which should be used to estimate population variance.
278 exam-style questions on CCEA A Level Maths 2.5 Data presentation and interpretation, covering 2.5.1 Data presentation and interpretation, 2.5.2 Data presentation and interpretation, 2.5.3 Data presentation and interpretation, 2.5.4 Data presentation and interpretation, 2.5.5 Data presentation and interpretation, 2.5.6 Data presentation and interpretation, 2.5.7 Data presentation and interpretation, 2.5.8 Data presentation and interpretation, 2.5.9 Data presentation and interpretation, and 2.5 Data presentation and interpretation. Each one has a worked solution and a mark scheme showing where the marks go.