Mr and Mrs Brown and their son John all drive. the family car. Before ordering a new car they decide to list in order their preferences for five optional extras independently. The rank order of their choices is as shown: Mrs Brown John Optional extra Mr Brown Heated rear window 1st. 2nd 3rd Anti-rust treatment 2nd 4th 2nd Headrests 3rd 1st 1st Inertia reel seat belts 4th 5th 5th Radio 5th 3rd 4th

(a) Calculate coefficients of rank correlation - between each pair of members of the Brown family.

(b) A salesman offered to supply three of these extras free with the new car. The family agreed to choose those three which were ranked highest by the two members who agreed most. Which three did they choose, and in what order? (L. Additional)