Water voles are becoming very rare; they are often confused with water rats. A naturalist society decided to record details of the water voles in their area. The members measured the weight (y) to the nearest 10 grams, and the body length (x) to the nearest millimetre, of eight active healthy water voles. The data they collected are in the table. Body Length (x) mm 140 150 170 180 180 200 220 220 Weight (y) grams 150 180 190 220 240 290 300 310 a Draw a scatter diagram of these data. b Give a reason to support the calculation of a regression line for these data. Use the coding and w-to work out the regression line of won I. d Find the equation of the regression line for y on x. e Draw the regression line on the scatter diagram. f Use your regression line to calculate an estimate for the weight of a water vole that has a body length of 210 mm. Write down, with a reason, whether or not this is a reliable estimate. The members of the society remove any water voles that seem unhealthy from the river and take them into care until they are fit to be returned. They find three water voles on one stretch of river which have the following measurements. A: Weight 235 gm and body length 180 mm B: Weight 180 gm and body length 200 mm C: Weight 195 gm and body length 220 mm g Write down, with a reason, which of these water voles were removed from the river.

AppendixLO1