Question

Justin is making snowballs to build a fort on the winter break. Justin can build 15 snowballs in an hour but 2 snowballs melt every 15 minutes. How long will it take him to build 210 snowballs?

Answer 1

Dear student
$$\begin{gathered} \mathrm{Let}\mathrm{y}=\mathrm{total}\mathrm{snowballs}\mathrm{afetr}\mathrm{x}\mathrm{hours}\mathrm{making}\mathrm{them} \\ \mathrm{So},\mathrm{ATQ} \\ \mathrm{y}=15\mathrm{x}-2\left(4\mathrm{x}\right) \\ \mathrm{Note}\mathrm{that}4\mathrm{x}\mathrm{is}\mathrm{the}\mathrm{number}\mathrm{of}15\mathrm{minute}\mathrm{periods}\mathrm{in}\mathrm{x}\mathrm{hours} \\ \Rightarrow \mathrm{y}=15\mathrm{x}-8\mathrm{x} \\ \Rightarrow \mathrm{y}=7\mathrm{x} \\ \Rightarrow 210=7\mathrm{x} \\ \Rightarrow \mathrm{x}=30 \\ \mathrm{So},\mathrm{he}\mathrm{will}\mathrm{make}\mathrm{snowballs}\mathrm{in}30\mathrm{hours} \end{gathered}$$
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