 Basic Mathematics

# 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 at the start of 2011 than at the start of 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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