$9-$mm$-$diameter spherical ball at $50$C is covered by a $1-$mm$-$thick plastic

insulation $($k$=0\mathrm{.}13$ W$/$m$$K$).$ The ball is exposed to a medium at $15$C with a combined

convection and radiation heat transfer coefficient of $20$ W$/$m$2$K$.$ Determine if the plastic

insulation on the ball will increase or decrease heat transfer from the ball