$[15]($Outcome n$)$ A hot air balloon is $25$ m in diameter. The surrounding air

density is $1\mathrm{.}14k\frac{g}{m^3}.$ The hot gas inside has a density of $0\mathrm{.}89k\frac{g}{m^3}.$ If the

balloon and basket combined weigh $300$ N $,$ how much additional payload

can the balloon lift? $($See example $2\mathrm{.}9)$