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Obra drove 160π meters along a circular track....

This topic has 1 expert reply and 0 member replies

Obra drove 160π meters along a circular track....

Post Wed Jan 24, 2018 8:47 am
Obra drove 160π meters along a circular track. If the area enclosed by the circular track on which she drove is 57,600π square meters, what percentage of the circular track did Obra drive?

A. 6.67%
B. 12.5%
C. 18.75%
D. 25%
E. 33.3%

The OA is the option E.

What is the equation I should set to get an answer here? Experts, I ask for your help. Thanks in advanced.

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DavidG@VeritasPrep Legendary Member
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Post Thu Jan 25, 2018 8:28 am
Vincen wrote:
Obra drove 160π meters along a circular track. If the area enclosed by the circular track on which she drove is 57,600π square meters, what percentage of the circular track did Obra drive?

A. 6.67%
B. 12.5%
C. 18.75%
D. 25%
E. 33.3%

The OA is the option E.

What is the equation I should set to get an answer here? Experts, I ask for your help. Thanks in advanced.
We're given: r^2 * π = 57,600 * π

r^2 = 57,600

r = 240. (Hopefully, you recognize that 24^2 = 576.)

If r = 240, then the circumference = 2πr = 2*240*π = 480π.

She's gone 160π, or 160π/480π = 1/3 = 33.33...%. The answer is E

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