Write down the value of r .

Find ${u_6}$ .

Find the sum to infinity of this sequence.

$r = \frac{{16}}{{32}}\left( { = \frac{1}{2}} \right)$     A1     N1

[1 mark]

correct calculation or listing terms     (A1)

e.g. $32 \times {\left( {\frac{1}{2}} \right)^{6 - 1}}$ , $8 \times {\left( {\frac{1}{2}} \right)^3}$ , 32, $\ldots$ 4, 2, 1

${u_6} = 1$     A1     N2

[2 marks]

evidence of correct substitution in ${S_\infty }$      A1

e.g. $\frac{{32}}{{1 - \frac{1}{2}}}$ , $\frac{{32}}{{\frac{1}{2}}}$

${S_\infty } = 64$     A1     N1

[2 marks]

This question was very well done by the majority of candidates. There were some who used a value of r greater than one, with the most common error being $r = 2$ .

This question was very well done by the majority of candidates. There were some who used a value of r greater than one, with the most common error being $r = 2$ . 

A handful of candidates struggled with the basic computation involved in part (c).