Distance travelled by an object in a particular second.
$s_{t}=u+\frac{1}{2} \,g(2 t-1)$
For $1 \,s$
$s_{1}=0+\frac{1}{2} \,g\,\,...(i)$
For $2\, s$
$ s_{2} =0+\frac{1}{2} \,g(4-1) $
$ =\frac{1}{2}\, g \times 3\,\,...(ii) $
For $3\, s$
$s_{3}=0+\frac{1}{2} \,g\,(6-1)=\frac{1}{2}\, g \times 5\,\,...(iii)$
The ratio of distance
$s_{1}: s_{2}: s_{3}=\frac{1}{2}\,g:\, \frac{3}{2}\, g: \frac{5}{2} \,g $
$=1: 3: 5$