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Percents
Math
Middle School Math

 Name _____________________________ Date ___________________
Percent
Complete.
 1 According to the Internal Revenue Service, 16.7 percent of the people who fill out federal income tax forms leave out pertinent information. Having to send back tax forms slows down the operation of the IRS. According to IRS figures, how many people out of six thousand will leave out pertinent information on their forms (round to the nearest person)?
 2 Edgewater Elementary School recently participated in a survey done by the local university. The College of Education had made an arrangement with our principal for the survey. They wanted to determine if students thought male teachers or female teachers were more lenient. 30% of the students thought female teachers were more lenient, 7% said they were the same, 4% had no opinion, and the rest of the students said male teachers were more lenient. On the day of the survey, there were four hundred sixty-seven students at school. How many said male teachers were more lenient?

Complete.
 1 Kaylee is performing an experiment using gel electrophoresis. She is monitoring the migration of RNA through the gel. The shortest fragments of RNA have traveled 4.7 cm through the gel and the longest fragments have traveled only 2.5 cm. The longest fragments have traveled what percent of the distance of the shortest fragments? Round your answer to the nearest hundredth of a percent.
 2 The initial population of protists in a culture is 4,568. The final population after one week was 8,168. The population increased by what percent over the week? Round your answer to the nearest hundredth of a percent.

Complete.
 1 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 2.5 million tons per year were removed 30 years ago, what is the current ore removal rate? Express your answer using scientific notation.
 2 A soil sample from the nearby power plant has 189 grams of sand in every kilogram of soil. What percent of the soil is made up of sand?

 Key #2
Complete.
 1 Ohm's law states that the voltage drop across a resistance is equal to the current flow through the resistor times the resistance of the resistor (V = IR). An apparatus is set up to make sure the voltage drop across the resistor is kept at a constant 9 volts. Two circuits are tested. In one the resistance (R1) of a single resistor is 1,000 ohms and in the second circuit the resistance of resistor (R2) is 1,500 ohms. Assuming Ohm's law holds perfectly true, the current (I) through R1 should be greater than that of R2 by what percent? Round your answer to the nearest hundredth of a percent.
 2 Racer Joe made four laps around Smallville racetrack with an average speed of 189.6 miles per hour. Speedy Bob made a set of four laps with an average speed of 193 miles per hour. Bob's speed was what percent of Joe's speed? Round your answer to the nearest hundredth of a percent.

Complete.
 1 A sample of clay is found in Mongolia that contains aluminum, silicon, hydrogen, magnesium, iron, and oxygen. The amount of iron is equal to the amount of aluminum. If the clay is 25% silicon, 12% hydrogen, 12% magnesium and 15% oxygen, what is the percent iron?
 2 What is the concentration (in %) of a solution of 800 ml of water that has 13 grams of barium chloride dissolved in it? Round your answer to the nearest hundredth of a percent if needed.

Complete.
 1 Lauren is a good scorer for her soccer team. She scored 9 goals during regular play, and she scored 4 on penalty kicks. What percent of her goals did not result from penalty kicks? Round your answer to the nearest tenth of a percent.
 2 Natalie ran the 100-meter dash in 12.16 seconds yesterday at track practice. Her friendly competitor (and twin sister) Destiny ran it in 14.6 seconds. Natalie's time differed from her sister's by what percent? Round your answer to the nearest hundredth of a percent.

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