1. The mass of a garden pot filled with water is $2000 \mathrm{~g}$. If $20 \%$ of the water is poured out, the total mass will decrease to $88 \%$ of the original mass. Calculate:

a) the mass of the water; b) the mass of the empty pot.
Solution: $88\%$ of the water in the pot is $1760 \mathrm{~g}$ $(88\% \cdot 2000=1760)$. Therefore, the mass of the evaporated water is $2000 \mathrm{~g}-1760 \mathrm{~g}$ $=240 \mathrm{~g}$. This mass represents $20\%$ of the water's mass. a) In the pot, there was $5.240 \mathrm{~g}=1200 \mathrm{~g}$ of water. b) The mass of the pot is $2000 \mathrm{~g}-1200 \mathrm{~g}=800 \mathrm{~g}$.