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# Percentages

Which is larger: 30% of 10, or 10% of 30? Are they the same?

# Percentage Change

When you freeze a full bottle of water, the bottle will become swollen. This is because water expands its volume by approximately $$10\%$$ when frozen. If you freeze $$25\text{ L}$$ of liquid water, what will be its frozen volume in liters?

A survey showed that the total population growth in Las Vegas since 2010 has been $$13\text{%}$$ per year. If the population of Las Vegas in 2010 was 2 million, how many more people lived in Las Vegas in 2011 than in 2010?

Your height a year ago was $$140\text{ cm}$$ and your height today is $$161\text{ cm}.$$ If your weight has shown exactly the same percentage growth as your height, and your weight one year ago was $$60\text{ kg},$$ how much weight, in kg, have you gained?

You answered $$14$$ questions correctly on a $$20$$-question test last month. Today, you answered $$17$$ questions correctly on another $$20$$-question test. This means you scored $$\clubsuit\text{%}$$ last month and $$\spadesuit\text{%}$$ today, showing a remarkable improvement. What is the improvement (in percentage) $$\spadesuit-\clubsuit?$$

John is looking for a new job that pays a higher salary than his current job which pays $$2000$$ a month. If Wal-Mart offers a monthly salary of $$2500$$ and John takes the job with Wal-Mart, what is the percentage increase in his salary?

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