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Percents
Math
Middle School Math

 

Name _____________________________
Date ___________________
Percents
Complete.

1.   In Bigtown Creek the flow of sediment is slowly decreasing as more and more of the drainage area around the creek is developed and covered by concrete. Ten years ago a measurement was made by the local university and an average mass of about 13 grams of sediment per hour was moving down the creek. Now the average sediment flow is only about 40% of that. What is the current mass sediment flow? Round your answer to the nearest tenth.

2.   A soil sample from the nearby power plant has 163 grams of sand in every kilogram of soil. What percent of the soil is made up of sand?

3.   The old mine near Smallville used to produce a lot of silver ore. The ore deposit has been pretty much depleted now though. Today the ore removal is only about 28% of what is was 30 years ago. If an average of 2 million tons per year were removed 30 years ago, what is the current ore removal rate? Express your answer using scientific notation.

4.   * This is a pre-made sheet.
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5.   Soils with a lot of clay hold more water than soils that have less clay. Let's say you have two soil samples of equal mass (16 grams each) that are composed mostly of sand and clay. Sample one is found to be 20% water and sample two is found to be 29% water. If you had to make a choice, which one do you think had the most clay in it?

6.   A soil sample from Mr. Bloop's farm was sent to the county agriculture department for analysis. It was found to consist of 23% sand, 28.8% silt, 31.2% clay, 5% gravel and the rest was humus. What percent of the sample was humus?


 


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Percents
Math
Middle School Math