Use $v=sqrtmu((2/r)-(1/a))$, perihelion = $a(1-e)$ and aphelion $= a(1+e)$.
Here e = 0.25, approximately.
Now, for any planet, the ratio of the speeds at perihelion and aphelion becomes
$sqrt((1+e)/(1-e))$ and here it is $sqrt( 1.25/0.75)=sqrt(5/3)$.