12 multiple-choice questions, progressively harder.
A right pipe is 8 cm long, open at both ends, and has wall thickness 2 cm. Its material volume is 192π192\pi192π cubic centimeters. What is the outer radius?
Solution
Correct answer: D
The annular area is 24 pi square centimeters. Factor the difference of squared radii.
With thickness 2 cm, the radius sum is 12 cm. The radii are 7 and 5 cm, so the outer radius is 7 cm.
A solid capsule has radius 2 cm and volume 200π3\frac{200\pi}{3}3200π cubic centimeters. It consists of a right cylinder and two hemispheres of that radius. Find its full tip-to-tip length.
Correct answer: B
The two hemispheres contribute 32 pi divided by 3 cubic centimeters.
The cylinder length is 14 cm. Add two radius-length ends to obtain full length 18 cm.
A rectangular block has a face 8 cm by 6 cm and unknown perpendicular thickness h. A radius-2 cm cylindrical bore passes through that thickness, strictly inside the face. The retained material volume is (336−28π)(336-28\pi)(336−28π) cubic centimeters. Find h.
Correct answer: C
For each centimeter of thickness, the retained cross-sectional area is 48 minus 4 pi square centimeters.
The right side is seven times the positive cross-sectional area, so h is 7 cm.
A side-10 cm cube has a radius-3 cm cylindrical blind cavity drilled 4 cm down from its top, strictly inside that top face. Find all exposed area, including the cavity wall and floor as well as the cube's underside.
Correct answer: A
The opening removes one disk, while the cavity floor adds one disk of the same radius. These cancel in the area count.
The area is (600+24π)(600+24\pi)(600+24π) square centimeters.
A right circular cylinder of radius 4 cm has one same-radius hemisphere attached to an end. The exposed boundary consists of the cylinder curved side and hemisphere curved side only; the other flat end is covered by a support. That exposed area is 96π96\pi96π square centimeters. Find the cylinder length.
There is no included flat disk.
The hemisphere curve uses 32 pi square centimeters, leaving 64 pi for the cylinder side. Its length is 8 cm.
A rectangular box has perpendicular base edges 6 cm and 10 cm. Its space diagonal is 14 cm. What is its exact height?
Subtract both squared base edges from the squared space diagonal.
The square is 60 square centimeters. The positive height is 2152\sqrt{15}215 cm.
A right pipe has outer radius 6 cm, length 8 cm, and material volume 160π160\pi160π cubic centimeters. Both ends are open. Find the area of every exposed material surface, including the inside and both end annuli.
The volume determines the inner radius.
This gives inner radius 4 cm. Now count both walls and both rings.
The exposed area is 200π200\pi200π square centimeters.
Two solid parts meet along one matching rectangle 5 cm by 3 cm. Their interiors do not overlap and there is no other contact. The assembled exterior area is 216 square centimeters. What was the sum of their separate total surface areas?
Assembly hides two copies of the 15-square-centimeter join. Restore both to recover the separate total.
The original sum was 246 square centimeters.
A right stepped prism has constant depth 3 cm. Its lower block is 10 cm wide and 4 cm high. An upper block of width 4 cm adds unknown height x over the left side. Its total volume is 276 cubic centimeters. Find the added height x.
The lower block occupies 120 cubic centimeters. The added block has base area 12 square centimeters.
Its volume is 156 cubic centimeters, so the added height is 13 cm.
A rectangular box has perpendicular edges 222\sqrt222 cm, 4 cm, and 7 cm. Find the exact space diagonal.
Square the whole radical edge, then add the three edge squares.
The square is 73 square centimeters, so the positive diagonal is 73\sqrt{73}73 cm.
A hollow hemispherical bowl is formed by removing a concentric radius-4 cm hemisphere from a radius-6 cm solid hemisphere. The flat circular mouths lie in the same plane. Find all exposed area, including both curved walls and the flat rim annulus.
The inner curved wall is added to the boundary count. The opening has no disk across it, but the rim is an annulus.
The exposed area is 124π124\pi124π square centimeters.
A solid hemisphere of radius 5 cm is joined by its entire flat disk to the base of a right cone of radius 5 cm and perpendicular height 12 cm. Find the exterior area.
The cone slant height is 13 cm by Pythagoras. Only the two curved surfaces are exposed.
The exterior area is 115π115\pi115π square centimeters.
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