Answer:
7. 5/2 . . . (scale factor and ratio of perimeters are the same)
9. 19"
Explanation:
7. The ratio of areas is the square of the scale factor, so ...
scale factor = √((75 m^2)/(12 m^2)) = √(25/4) = 5/2
The ratio of perimeters is the same as the scale factor.
The scale factor and ratio of perimeters is 5/2.
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9. The difference in distances is the difference in wheel circumferences. The circumference is π times the diameter, so you want
difference = (31π) -(25π) = π(31 -25) = 6π ≈ 18.8 . . . . inches
The truck travels about 19 inches farther on each revolution of the wheel.