Mensuration Questions

Multiple choice
  1. $75 π cm2$
  2. $125 π cm2$
  3. $150 π cm2$
  4. $100 π cm2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A sphere has surface area 4πr². When divided into two hemispheres, each hemisphere has curved surface area 2πr² plus circular base area πr², giving total 3πr² per hemisphere. For two hemispheres: 2×3πr² = 6πr² = 6π(5)² = 150π cm². Option B (125π) incorrectly uses 5πr² formula, and options A and D don't match the correct calculation.

Multiple choice
  1. 2140 cm2

  2. 2150 cm2

  3. 2170 cm2

  4. 2155 cm2

  5. 2175 cm2

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

Let the radii be 2r and 3r (given ratio 2:3). Circumference = 2πR, so 2π(2r) + 2π(3r) = 220. This gives 10πr = 220, so r = 7 (using π = 22/7). Larger circle radius = 21 cm, area = π(21)² = 1386 cm². Square side = 2 × smaller radius = 2 × 14 = 28 cm. Square area = 784 cm². Total area = 1386 + 784 = 2170 cm².

Multiple choice
  1. 14 m

  2. 12 m

  3. 20 m

  4. 18 m

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

Total volume = cylinder volume + hemisphere volume. Hemisphere volume = (2/3)πr³ = (2/3)π(6)³ = 144π m³. Cylinder volume = 576π - 144π = 432π m³. Using V = πr²h, we get π(6)²h = 432π, so h = 12 m. Total height = cylinder height + hemisphere height = 12 + 6 = 18 m.

Multiple choice
  1. 132πcm2

  2. 143 πcm2

  3. 156 πcm2

  4. 168 πcm2

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

For a right circular cone with height h = 5 cm and base radius r = 12 cm, first find the slant height l using Pythagoras theorem: l = √(h² + r²) = √(25 + 144) = √169 = 13 cm. The curved surface area is πrl = π × 12 × 13 = 156π cm². Option A incorrectly uses l = 11, giving 132π. Option B uses incorrect dimensions.

Multiple choice
  1. $56 m2$
  2. $60 m2$
  3. $120 m2$
  4. $84 m2$
  5. None of these

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

Hall area = 20 × 15 = 300 m². Each tile = 1.5 × 2 = 3 m². Total tiles = 300/3 = 100. Blue tiles = 20% of 100 = 20. Yellow tiles = 30% of remaining 80 = 24. Red tiles = 50% of remaining 56 = 28. White tiles = remaining = 56 - 28 = 28. White tile area = 28 × 3 = 84 m², which is option D.

Multiple choice
  1. 234

  2. 243

  3. 432

  4. 324

  5. None of these

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

Volume of hemisphere = (2/3)πr³ = (2/3)π(39)³ = 39462π cm³. Volume of one cone = (1/3)πr²h = (1/3)π(13)²(3) = 169π cm³. Number of bottles = 39462π/169π = 233.5, which rounds to 234 complete bottles. The key is equating total volume and computing the ratio.

Multiple choice
  1. 2156

  2. 2183

  3. 2492

  4. None of these

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

CSA: TSA = 2:3, so CSA = (2/3)×924 = 616. For cylinder: TSA = 2πr(r+h) = 924, CSA = 2πrh = 616. Dividing: h/(r+h) = 616/924 = 2/3, so 3h = 2r + 2h, giving h = 2r. From 2πr(3r) = 924, r = 7, h = 14. Volume = πr²h = π×49×14 = 2156.

Multiple choice
  1. I and III

  2. II and III

  3. All I, II and III

  4. Can’t be answered using all the above statements.

  5. None of the above.

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

From I: Length = 6m. From II: Breadth = (2/3)*6 = 4m. Area = 6*4 = 24m² = 240000 cm². From III: Cost of 100 cm² = Rs 45, so cost per cm² = Rs 0.45. Total cost = 240000 * 0.45 = Rs 108000. All three statements are needed: I and II give dimensions, III gives rate. Without any one, the answer cannot be determined.

Multiple choice
  1. Quantity I > Quantity II

  2. Quantity I ≥ Quantity II

  3. Quantity II > Quantity I

  4. Quantity II ≥ Quantity I

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

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

Rectangle perimeter = 2(11+10) = 42 cm. Square perimeter = 2 × 42 = 84 cm, so side = 21 cm. Quantity I: Semicircle with diameter 21 cm has radius 10.5 cm. Circumference of semicircle = πr + 2r = (π × 10.5) + 21 ≈ 33 + 21 = 54 cm. Quantity II: Semicircle with radius 14 cm has circumference = πr + 2r = (π × 14) + 28 ≈ 44 + 28 = 72 cm. Clearly 72 > 54, so Quantity II exceeds Quantity I.

Multiple choice
  1. 2484 cm2

  2. 2556 cm2

  3. 2520 cm2

  4. 2448 cm2

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

The triangle with sides 20, 21, 29 is a right triangle (20² + 21² = 29²). Base area = (1/2) × 20 × 21 = 210 cm². Height = Volume / Base area = 7560 / 210 = 36 cm. Lateral surface area = Perimeter × Height = (20 + 21 + 29) × 36 = 2520 cm².

Multiple choice
  1. 25

  2. 26

  3. 27

  4. 28

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

Sphere surface area 4πr² = 616, so r² = 49, r = 7 cm. Volume of sphere = (4/3)πr³ = 1437.33 cm³. Cone has same radius (7 cm) and same volume (conserved). (1/3)πr²h = 1437.33, so h = (1437.33 × 3) / (π × 49) = 28 cm. Option C (27 cm) is close but incorrect.

Multiple choice
  1. Quantity I > Quantity II

  2. Quantity I ≥ Quantity II

  3. Quantity II > Quantity I

  4. Quantity II ≥ Quantity I

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

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

Quantity I: Rectangle sides in ratio 20:9, perimeter = 116 cm. Let sides be 20x and 9x. Perimeter = 2(20x + 9x) = 58x = 116, so x = 2. Area = 20x × 9x = 180x² = 180 × 4 = 720 cm². Quantity II: Cylinder radius = 14 cm. Height = side of square with area 64 cm², so side = 8 cm. Curved surface area = 2πrh = 2 × π × 14 × 8 = 224π ≈ 704 cm². Since 720 > 704, Quantity I > Quantity II. However, the claimed answer is A which states 'Quantity I > Quantity II', so agrees = true.

Multiple choice
  1. 81.5 cm2

  2. 100.75 cm2

  3. 75.75 cm2

  4. 78.25 cm2

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

Triangle with sides 10, 24, 26 is right-angled (10²+24²=26²). Area = ½ × 10 × 24 = 120 cm². Sectors at vertices have radii 3.5 cm and angles equal to the vertex angles (sum = 180° for right triangle). Total sector area = (180/360) × π × 3.5² = ½ × 38.48 = 19.24 cm². Area excluding sectors = 120 − 19.24 = 100.76 ≈ 100.75 cm². Wait, that assumes sum of angles is 180°, but in a right triangle, the three angles sum to 180°, with one angle = 90°. So total sector area = (90/360 + A/360 + B/360) × πr² = (180/360) × πr² = 19.24. Then 120 − 19.24 = 100.76, which rounds to 100.75. Option B is correct.