12 multiple-choice questions, progressively harder.
Similar solids have corresponding lengths 7 cm in the original and 21 cm in the image. What factor takes original lengths to image lengths?
Solution
Correct answer: B
Divide image length by original length.
A solid is resized uniformly by positive length factor 4. What is its surface-area factor?
Correct answer: D
Surface area uses two length factors.
A similar image has length factor 3/23/23/2. What is its image-to-original volume factor?
Correct answer: A
Cube the positive length factor.
Every length of a solid is multiplied by 1/41/41/4. What factor multiplies its volume?
Correct answer: C
All three dimensions shrink.
A sphere has radius 4 cm. A similar image has radius 6 cm. What is the surface-area factor?
All spheres are similar. The radius gives the length factor.
Similar solids have corresponding perpendicular heights 6 cm and 9 cm, in original:image order. The original volume is 80 cubic cm. What is the image volume?
The height ratio gives the common length factor. Cube it for volume.
Surface area is measured in square centimeters and volume in cubic centimeters. What unit does surface area divided by volume have?
Two powers of centimeters cancel from numerator and denominator.
A solid has total surface area 54 square cm and volume 27 cubic cm. What is its surface-area-to-volume ratio?
Divide surface area by volume, keeping the resulting units.
Two similar solids have volume ratio original:image of 1:1251:1251:125. What is their corresponding length ratio in the same order?
Take positive cube roots of the volume-ratio parts.
Two similar solids have surface-area ratio original:image of 9:169:169:16. What is their corresponding length ratio in the same order?
Positive square roots recover a length ratio from the surface-area ratio.
A rectangular box changes from 3 by 4 by 6 cm to 3 by 4 by 12 cm, with the named dimensions corresponding in order. Which description is correct?
The first two dimensions have factor 1, but the third has factor 2. One common length factor does not exist.
A right cylinder keeps its radius fixed and triples its perpendicular height. What happens to its volume?
The base area stays fixed, while the height has factor 3.
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