(a(i))[1]
Explain why $87$ is not a possible total for the number of bags in the box.
(a(ii))[3]
The mean number of sweets in each bag in this box is $12.8$. Find the value of $p$.
(b(i))[3]
A bag of sweets is selected at random from this box and not put back. A second bag of sweets is then selected at random from the same box. The probability that both bags contain $15$ sweets is $\frac{4}{539}$. Show that $r^2 + 175r - 2046 = 0$.
(b(ii))[3]
Solve $r^2 + 175r - 2046 = 0$ to determine $r$. Show your working.