A data set contains points (1,3),(2,5),(3,7),(4,9)(1,3),(2,5),(3,7),(4,9)(1,3),(2,5),(3,7),(4,9) and (10,k)(10,k)(10,k). Without the fifth point, all points lie on y=2x+1y=2x+1y=2x+1.
Find the value of k k\,k that places the fifth point on the same line.
If k=−20k=-20k=−20, describe the likely effect of the fifth point on the fitted regression line.
State one check to make before deciding whether to remove it.
121 exam-style questions on OCR A Level Maths 2.2 Data Presentation and Interpretation, covering 2.2.1 Tables and diagrams for single variable data, 2.2.2 Area in a histogram, 2.2.3 Scatter diagrams and regression lines, 2.2.4 Informal interpretation of correlation, 2.2.5 Correlation and causation, 2.2.6 Measures of average and spread, 2.2.7 Calculations of mean and standard deviation, 2.2.8 Outliers, 2.2.9 Selecting or critiquing data presentation, and 2.2.10 Cleaning data. Each one has a worked solution and a mark scheme showing where the marks go.