18N.2.SL.TZ0.S_2
The following table shows the hand lengths and the heights of five athletes on a sports team.
The relationship between x and y can be modelled by the regression line with equation y = ax + b.
Find the value of a and of b.
[3]
a.i.
Write down the correlation coefficient.
[1]
a.ii.
Another athlete on this sports team has a hand length of 21.5 cm. Use the regression equation to estimate the height of this athlete.
[2]
b.
Markscheme / solution
evidence of set up (M1)
eg correct value for a or b or r (seen in (ii)) or r2 (= 0.973)
9.91044, −31.3194
a = 9.91, b = −31.3, y = 9.91x − 31.3 A1A1 N3
[3 marks]
a.i.
0.986417
r = 0.986 A1 N1
[1 mark]
a.ii.
substituting x = 21.5 into their equation (M1)
eg 9.91(21.5) − 31.3
181.755
182 (cm) A1 N2
[2 marks]
b.
Examiners’ report
[N/A]
a.i.
[N/A]
a.ii.
[N/A]
b.