A wheel has a diameter of x inches and a second wheel has a diameter of y inches. The first wheel covers a distance of d feet in 100 revolutions. How many revolutions does the second wheel make in covering d feet?
A. 100xy
B. 100y - x
C. 100x - y
D. 100y / x
E. 100x / y
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Wheel Revolutions
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harsh.champ
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sadullaevd
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Diameters: X and Y
One Rotation distance: X pi and Y pi
Then --> d=100Xpi and d = R(variable for Rotation) Ypi
Putting them together: RYpi=100Xpi
R=100x/y
IMO E
One Rotation distance: X pi and Y pi
Then --> d=100Xpi and d = R(variable for Rotation) Ypi
Putting them together: RYpi=100Xpi
R=100x/y
IMO E
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thephoenix
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one rev of x inch dia wheel=pix inchharsh.champ wrote:A wheel has a diameter of x inches and a second wheel has a diameter of y inches. The first wheel covers a distance of d feet in 100 revolutions. How many revolutions does the second wheel make in covering d feet?
A. 100xy
B. 100y - x
C. 100x - y
D. 100y / x
E. 100x / y
100 rev=100 pi *x inch=12d inch
one rev of y inch dia wheel=pi * y inch
or pi*y inch = 1 rev of y inch dia wheel
so 12d inch =[1/(pi*y)] *12d=put 12d from eqn 1=100 *pi *x/pi*y=100 x/y =E
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shashank.ism
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so for 1st wheel 2pi x = d/100 --> d= 100 (2pi x )harsh.champ wrote:A wheel has a diameter of x inches and a second wheel has a diameter of y inches. The first wheel covers a distance of d feet in 100 revolutions. How many revolutions does the second wheel make in covering d feet?
A. 100xy
B. 100y - x
C. 100x - y
D. 100y / x
E. 100x / y
for 2nd wheel 2pi y = d/rev --> rev = d/(2 pi y) --> rev = 100 (2pi x )/2 pi y = [spoiler]100x/y Ans E[/spoiler]
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Jeff@TargetTestPrep
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Recall that d feet = 12d inches and the circumference (C = 2πr or Dπ) of the x-inch diameter wheel = xπ and that of the y-inch diameter wheel = yπ.harsh.champ wrote:A wheel has a diameter of x inches and a second wheel has a diameter of y inches. The first wheel covers a distance of d feet in 100 revolutions. How many revolutions does the second wheel make in covering d feet?
A. 100xy
B. 100y - x
C. 100x - y
D. 100y / x
E. 100x / y
Therefore, we know that in 1 revolution, the first wheel covers a distance of xπ inches. Thus, in 100 revolutions, it covers 12d inches, as shown here:
xπ * 100 = 12d
If we let r = the number of revolutions the second wheel makes, we have:
yπ * r = 12d
Thus, we have:
xπ * 100 = yπ * r
100x = yr
100x/y = r
Answer: E
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