Question 9 • (OC27) MATH COLL ALGEBRA-1200710-S1-Degele-VOL7006P
Read the word problem below.Chan rows at a rate of eight miles per hour in still water. On Wednesday, it takes him three hours to row upstream from his house to the park. He rows back home, and it takes him two hours. What is the speed of the current? Which of the following is a clue that would help solve this word problem?
Answer
A
The rate of Chan’s rowing in still water is 8 mph.
B
Chan rows from the house to the park on Wednesday.
C
Chan’s house is next to a river.
D
The entire trip takes five hours.
Explanation
The useful clue is that Chan rows at 8 mph in still water. If the current’s speed is c, his upstream speed is 8 − c and his downstream speed is 8 + c. The equal trip distances give 3(8 − c) = 2(8 + c), so c = 1.6 mph. Thus, the clue is “The rate of Chan’s rowing in still water is 8 mph.”
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