Correct the intermediate expansion before solving for the percentage

p% of students take Mathematics A and the remaining(100−p)% take Mathematics B.30% of Math A students fail and 40% of Math B students fail.

(i) Show that the probability exactly one of two students fails is $0.0002(2400-2p-0.01p^2)$.5 marks

(ii) Given the probability both take Math A, conditional on exactly one failing, is $7/48$, find p.3 marks