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Unformatted text preview: hard caught up to Susie, the distances must be equal.
30 x = 45 x − 90 90 = 15 x x=6 Susie traveled for 6 hours, which means it was 6 hours past 11 A.M., or 5 P.M. when Richard caught up to her. Example: How far can Scott drive into the country if he drives out at 40 miles per hour and returns over the same road at 30 miles per hour and spends 8 hours away from home including a one-hour stop for lunch? Solution: His actual driving time is 7 hours, which must be divided into two parts. If one part is x, the other is what is left, or 7 – x. Rate Going Return The distances are equal.
40 x = 210 − 30 x 70 x = 210 x=3 · Time x 7–x = Distance 40x 210x – 30x 40 30 If he traveled 40 miles per hour for 3 hours, he went 120 miles. www.petersons.com 184 Chapter 12 Exercise 7
Work out each problem. Circle the letter that appears before your answer. 1. At 10 A.M. two cars started traveling toward each other from towns 287 miles apart. They passed each other at 1:30 P.M. If the rate of the faster car exceeded the rate of the slower car by 6 miles per hour, find the rate, in miles per hour, of the faster car. (A) 38 (B) 40 (C) 44 (D) 48 (E) 50 A motorist covers 350 miles in 8 hours. Before noon he averages 50 miles per hour, but after noon he averages only 40 miles per hour. At what time did he leave? (A) 7 A.M. (B) 8 A.M. (C) 9 A.M. (D) 10 A.M. (E) 11 A.M. At 3 P.M. a plane left Kennedy Airport for Los Angeles traveling at 600 m.p.h. At 3:30 P.M. another plane left the same airport on the same route traveling at 650 m.p.h. At what time did the second plane overtake the first? (A) 5:15 P.M. (B) 6:45 P.M. (C) 6:50 P.M. (D) 7:15 P.M. (E) 9:30 P.M. 4. Joe left home at 10 A.M. and walked out into the country at 4 miles per hour. He returned on the same road at 2 miles per hour. If he arrived home at 4 P.M., how many miles into the country did he walk? (A) 6 (B) 8 (C) 10 (D) 11 (E) 12 Two cars leave a restaurant at the same time and proceed in the same direction along the sam...
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This note was uploaded on 08/15/2010 for the course MATH a4d4 taught by Professor Colon during the Spring '10 term at Embry-Riddle FL/AZ.
- Spring '10