# Question 2(a):

Ranks correctly assigned (Mary: 3,4,1,8,2,5,7,9,6 and Jahil: 2,5,3,9,1,4,6,8,7) | M1 | Attempt to rank both – one row with at least 6 correct

$\sum d^2 = 1+1+4+1+1+1+1+1+1 = 12$ | M1 | Attempt to find $\sum d^2$ (some correct $d$ values found and sum attempted)

$r_s = 1 - \dfrac{6 \times 12}{9 \times 80}$ | M1 | For using their $\sum d^2$ in formula for $r_s$ with $n=9$

$= \mathbf{0.9}$ | A1 | For 0.9 or exact fraction e.g. $\frac{9}{10}$

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# Question 2(b):

Dawn's ranks assigned with tied ranks handled (Dawn: 7.5, 6, 9, 2, 7.5, 3, 4.5, 1, 4.5) | M1 | For ranking Dawn's results and dealing with tied ranks

$S_{JJ} = 60,\quad S_{DD} = 59,\quad S_{JD} = 176 - \dfrac{45^2}{9} = -49$ | M1 | For selecting appropriate method to find $r_s$ sight of 2 of these values or implied by answer

$r_s = 0 - 0.823558\ldots \quad$ awrt $\mathbf{-0.824}$ | A1 | For using calculator to evaluate $r_s$, allow awrt $-0.824$

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# Question 2(c):

Mary and Jahil gave points for good features or high score is good; Dawn gave points for poor features or low score is good | B1 | For idea that M and J gave points for good features but D for bad features

Both strong correlation, M&J positive, J&D negative so agree | B1 | For explaining that since both correlations are strong, one +, one − they agree

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