2011SP-I-06

16-06-2021 app.cch No Comments

Ans: (a)

3

(b)

54 {cm}^{3}

$\begin{array}{rcl} \frac{1}{3} π r^{2} (12) & = & 2 \times \frac{1}{2} \times \frac{4}{3} π r^{3} \\ 4 & = & \frac{4}{3} r \\ r & = & 3 \end{array}$
The volume of the solid
$\begin{array}{cl} = & \frac{1}{3} π (3)^{2} (12) + \frac{1}{2} \times \frac{4}{3} π (3)^{3} \\ = & 54 {cm}^{3} \end{array}$

2011SP, HKDSE-MATH, Paper 1 Mensuration