Jogging track

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Jogging track

by Baldini » Fri Mar 06, 2009 3:46 am
A circular jogging track forms the edge of a circular lake thta has a diameter of 2 miles. Johanna walked once around the track at an average rate of 3 mph. 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
e. 3<t<3.5

OA is c.
I get OA a. Could someone please explain why this is incorrect?
Thanks
GMAX
Source: — Problem Solving |

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by bluementor » Fri Mar 06, 2009 3:54 am
3*t = 2*pi*r
3*t = 2*pi*(d/2)
3*t = 2*pi
t= 2*pi/3
t= (2/3)*(22/7)
t= 44/21
t = 2 + 2/21

this value of t is larger than 2 by 2/21, and is definitely less than 2.5. Hence C.

-BM-