(a(i))[2]
Complete the probability expression for Angelo drawing two black counters.
(a(ii)(a))[4]
Show that the result is $4x^2-25x-21=0$.
(a(ii)(b))[3]
Solve $4x^2-25x-21=0$ using factorisation.
(a(ii)(c))[1]
Write down how many black counters are in the bag.
(b)[4]
Work out the probability that all three counters are the same colour.