New SAT Math Workbook

A b c d e rm p rp m p rm pm r m rp 5 2 apart

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Unformatted text preview: ) (B) (C) (D) (E) rm p rp m p rm pm r m rp 5. 2. apart are two towns that are 2 1 4 4 inches apart on the map? (A) (B) (C) (D) (E) 3. 11 45 22 1 2 1 40 2 42 The toll on the Intercoastal Thruway is 8¢ for every 5 miles traveled. What is the toll for a trip of 115 miles on this road? (A) $9.20 (B) $1.70 (C) $1.84 (D) $1.64 (E) $1.76 www.petersons.com Variation 59 3. INVERSE VARIATION Two quantities are said to vary inversely if they change in opposite directions. As the first increases, the second decreases. As the first decreases, the second increases. Whenever two quantities vary inversely, their product remains constant. Instead of dividing one quantity by the other and setting their quotients equal as we did in direct variation, we multiply one quantity by the other and set the products equal. There are several situations that are good examples of inverse variation. A) The number of teeth in a meshed gear varies inversely as the number of revolutions it makes per minute. The more teeth a gear has, the fewer revolutions it will make per minute. The less teeth it has, the more revolutions it will make per minute. The product of the number of teeth and the revolutions per minute remains constant. B) The distance a weight is placed from the fulcrum of a balanced lever varies inversely as its weight. The heavier the object, the shorter must be its distance from the fulcrum. The lighter the object, the greater must be the distance. The product of the weight of the object and its distance from the fulcrum remains constant. C) When two pulleys are connected by a belt, the diameter of a pulley varies inversely as the number of revolutions per minute. The larger the diameter, the smaller the number of revolutions per minute. The smaller the diameter, the greater the number of revolutions per minute. The product of the diameter of a pulley and the number of revolutions per minute remains constant. D) The number of people hired to work on a job varies inversely as the time needed to complete the job. The more peo...
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