completely around the lake

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completely around the lake

by sanju09 » Fri Apr 10, 2009 5:12 am
A circular jogging track forms the edge of a circular lake that has a diameter of 2 miles, Johanna walked once around the track at the average rate of 3 miles per hour. If t represents the number of hours it took Johanna to walk completely around the lake, which of the following is a correct statement?
A. 0.5 < t < 0.75
B. 1.75 < t < 2.0
C. 2.0 < t < 2.5
D. 2.5 < t < 3.0
E. None of the above



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by dmateer25 » Fri Apr 10, 2009 5:51 am
Circumference of the track = 2pi

2(3.14) = 6.28

RT = D

3T = 6.28
T = 6.28/3
T ~ 2.09

C

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by Jeff@TargetTestPrep » Tue Apr 10, 2018 10:22 am
sanju09 wrote:A circular jogging track forms the edge of a circular lake that has a diameter of 2 miles, Johanna walked once around the track at the average rate of 3 miles per hour. If t represents the number of hours it took Johanna to walk completely around the lake, which of the following is a correct statement?
A. 0.5 < t < 0.75
B. 1.75 < t < 2.0
C. 2.0 < t < 2.5
D. 2.5 < t < 3.0
E. None of the above
If the lake has a diameter of 2 miles, then its circumference (which is the length of the track) is 2 x π = 2π miles long. Since Johanna's speed is 3 miles per hour, then the time it took her to walk around the lake is 2π/3 hours. Since π ≈ 3.14, so 2π/3 ≈ 6.28/3 ≈ 6.3/3 = 2.1 hours.

Answer: C

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