Answer
$7.5$ sec, $1.2$ sec.
Work Step by Step
Step 1. Identify the equations: $s(t)=1.86t^2$ on Mars, $s(t)=11.44t^2$ on Jupiter.
Step 2. On Mars, $v(t)=s'(t)=2\times1.86t=3.72t$. Let $v(t)=27.8$; we have $3.72t=27.8$, which gives $t\approx7.5$ sec.
Step 3. On Jupiter, $v(t)=s'(t)=2\times11.44t=22.88t$. Let $v(t)=27.8$; we have $22.88t=27.8$, which gives $t\approx1.2$ sec.
