Alfonso runs 10 km at \(x\) km/h. Next day he runs 12 km at \(x-1\) km/h. The 10 km run takes 30 minutes less than the 12 km run.

(a(i)) Form an equation in \(x\) and show it simplifies to \(x^2-5x-20=0\). [4]

(a(ii)) Use the quadratic formula to solve the equation. Show working and give both answers to 2 decimal places. [4]

(a(iii)) Find the time for the 12 km run, in hours and minutes to the nearest minute. [2]

A cheetah runs for 60 seconds. Its speed-time graph is shown.

(b(i)) Find the acceleration in the first 10 seconds. [1]

(b(ii)) Find the distance travelled. [3]