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170

The number of revolutions per minute (RPM) varies inversely as the number of teeth of a gear. A certain gear that had 51 teeth resulted in 140 RPM. After the 51-tooth gear was replaced the one that had 42 teeth, how many RPMs did it do?

200

The number of revolutions per minute (RPM) varies inversely as the number of teeth of a gear. A certain gear that had 50 teeth resulted in 100 RPM. After the 50-tooth gear was replaced the one that had 25 teeth, how many RPMs did it do?

21

The number of birds varied directly as the number of bird feeders. When there were 7 feeders, there were 302 birds. When some more feeders were made, the number of birds increased to 1208. How many bird feeders were added?

3 1/5

The volume varied inversely as the pressure. When the pressure was 1 1/3 atmospheres, the volume was 6L. How many atmospheres of pressure would be needed to compact the volume to 2½L?

180

The number of people at the beach in varied directly as the temperature. When the temperature was 60⁰F, there were 120 people. Later on that day, the temperature rose to 90⁰F. How many people were there then?

1.5

If a 2 results in a 3, what will a 4 result in if the variation is inverse?

2093

If a 3 results in a 7, what will an 897 result in if the variation is direct?

8.4

If a 3.6 results in a 2.1, what will a 3 result in if the variation is inverse?