Mensuration Questions

Multiple choice
  1. 50%

  2. 25%

  3. 40%

  4. 75%

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Volume of cone = (1/3)πr²h = (1/3)π × 9² × 9 = 243π cubic cm. Volume of sphere = (4/3)πr³ = (4/3)π × 9³ = 972π cubic cm. Wood wasted = (Volume of sphere - Volume of cone) / Volume of sphere × 100 = (972π - 243π) / 972π × 100 = 729/972 × 100 = 75%. The cone carved out uses only 25% of the sphere's volume, leaving 75% as waste.

Multiple choice
  1. 14 cm

  2. 28 cm

  3. 7 cm

  4. 56 cm

  5. 24 cm

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For a cylinder, curved surface area (CSA) = 2πrh and total surface area (TSA) = 2πr(r + h). Given CSA:TSA = 4:5, so 2πrh / 2πr(r+h) = 4/5. Simplifying: h/(r+h) = 4/5, so 5h = 4r + 4h, giving h = 4r. With CSA = 1232 = 2πrh = 2πr(4r) = 8πr². Solving: r² = 1232/(8π) ≈ 49, so r = 7. Height h = 4r = 28 cm. Option B is correct.

Multiple choice
  1. (35 - 9π) m2

  2. (36 - 8π) m2

  3. (36 - 9π) m2

  4. (25 - 9π) m2

  5. None of these

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When four equal circles (diameter 6m, so radius 3m) touch each other externally, their centers form a square of side 6m. The area bounded by the circles is the area of this square minus the four quarter-circles (which together form one full circle). Square area = 36 m², Circle area = π × 3² = 9π m². Therefore, bounded region area = 36 - 9π m².

Multiple choice
  1. Rs. 2050

  2. Rs. 2060

  3. Rs. 2068

  4. Rs. 2080

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total surface area to paint = CSA of cylinder + CSA of cone. Cylinder: 2πrh = 2 × π × 14 × 3 = 84π. For the cone, slant height l = √(h² + r²) = √(10.5² + 14²) = √306.25 = 17.5m. CSA = πrl = π × 14 × 17.5 = 245π. Total area = 329π ≈ 1034 m². Cost = 1034 × 2 = Rs. 2068.

Multiple choice
  1. Quantity II > Quantity I

  2. Quantity I ≥ Quantity II

  3. Quantity I > Quantity II

  4. Quantity I ≤ Quantity II

  5. Quantity I = Quantity II or relationship cannot be established

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Quantity I: Cylinder volume = π × 14² × 196 = π × 196 × 196 = 38416π cm³. Cube volume = 7³ = 343 cm³. Number of cubes x = 38416π/343 ≈ 112π ≈ 352. Quantity II: Cone diameter = 1400 cm = 14 m, so radius = 7 m. CSA = πrl = 176, so π × 7 × l = 176, giving l = 176/(7π) ≈ 8 m. Height h = √(l² - r²) = √(64 - 49) = √15 ≈ 3.87 m = 387 cm. Quantity II ≈ 387 > Quantity I ≈ 352. Option A is correct.

Multiple choice
  1. Only II

  2. Only I

  3. I and II

  4. Any one of the two.

  5. None of these.

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Statement I alone gives only ratio (3:4), insufficient for area or cost. Statement II: Let dimensions be l and b. Diagonal = sqrt(l^2 + b^2), Perimeter = 2(l+b). Difference = 36. Combined with ratio 3:4, we can solve: let l=3x, b=4x. Diagonal = 5x, Perimeter = 14x, 14x-5x=9x=36, so x=4. Area = 12×16 = 192 sq cm. Both statements needed. Answer C is correct.

Multiple choice
  1. 530 cm³/सेमी.³

  2. 536 cm³/सेमी.³

  3. 539 cm³/सेमी.³

  4. 545 cm³/सेमी.³

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total surface area = 462 cm². Curved surface = (1/3) × 462 = 154 cm². So top + bottom = 462 - 154 = 308 cm². Each circular face area = 308/2 = 154 = πr², giving r = 7 cm. Curved surface = 2πrh = 154, so 2π × 7 × h = 154, giving h = 3.5 cm. Volume = πr²h = π × 49 × 3.5 = 539 cm³ (taking π = 22/7).

Multiple choice
  1. 3 : 4

  2. 4 : 3

  3. 3 : 2

  4. 2 : 3

  5. None of these

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When a cube is melted and recast, volume is conserved. The side lengths of cubes are proportional to the cube root of their volumes. Given volume ratio 1:1:8:27:27, the side ratio is 1:1:2:3:3. Surface area of a cube is proportional to the square of its side. Summing the surface areas of all five cubes and comparing to the original cube's surface area yields the ratio 3:2.

Multiple choice
  1. 1228

  2. 1723

  3. 1540

  4. 1617

  5. None of these

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

CSA:TSA = 3:5 means 2πrh:2πr(r+h) = 3:5, so h:(r+h) = 3:5, giving 5h = 3r + 3h, so h = 1.5r. Given CSA = 462, so 2πrh = 462. Substituting h = 1.5r: 2πr(1.5r) = 462. Using π = 22/7: r = 7 cm, h = 10.5 cm. Volume = πr²h = (22/7) × 49 × 10.5 = 1617 cm³.

Multiple choice
  1. 2640 cm3

  2. 2604 cm3

  3. 2460 cm3

  4. None of these

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For a hollow cylinder, the volume of material = π(R² - r²)h, where R is outer radius, r is inner radius (bore radius). Inner radius = 2.5 cm. Thickness = 1 cm, so outer radius = 2.5 + 1 = 3.5 cm. Length = 1.4 m = 140 cm. Volume = π[(3.5)² - (2.5)²] × 140 = π[12.25 - 6.25] × 140 = π(6) × 140 = 840π ≈ 2638.9 cm³. Rounding gives approximately 2640 cm³. Option B has incorrect digit order, while option C has different values.

Multiple choice
  1. 3

  2. 4

  3. 6

  4. 9

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let base width = x, then height = 2x. Volume of box = base area × height = x² × 2x = 2x³ = 54. Solving: x³ = 27, so x = 3. Height = 2x = 6 cm. The distractor 3 comes from confusing width with height, while 9 would result from using height = x².

Multiple choice
  1. 8 cm.

  2. 6 cm.

  3. 4 cm.

  4. 2 cm.

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Volume of cone = (1/3)πr²h = (1/3)π(2²)(8) = (32/3)π cm³. When melted and recast, volume remains constant. Volume of sphere = (4/3)πr³. Equating: (4/3)πr³ = (32/3)π, which gives r³ = 8, so r = 2 cm. Therefore diameter = 4 cm.