Answer
a) $3.56cm$ farther
b) $0.706cm$ closer
Work Step by Step
$d_o=150cm$
$f=\frac{1}{P}=\frac{1}{6.5D}=15.4cm$
$d_i=\frac{1}{\frac{1}{f}-\frac{1}{d_o}}=17.2cm$
a) For $d_o=60cm$
$d_i=\frac{1}{\frac{1}{f}-\frac{1}{d_o}}=20.7cm$
$3.56cm$ farther
b) For $d_o=240cm$
$d_i=\frac{1}{\frac{1}{f}-\frac{1}{d_o}}=16.5cm$
$0.706cm$ closer
