Mensuration Questions

Multiple choice
  1. $88$ cm
  2. $17.5$ cm
  3. $35$ cm
  4. $9.3$ cm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Circumference of inner circle = 2 * pi * r_inner = 88, so r_inner = 88 / (2 * pi) = 14 cm. Area difference = pi * (R^2 - r^2) = 346.5. R^2 - 14^2 = 346.5 / pi = 110.25. R^2 = 196 + 110.25 = 306.25. R = sqrt(306.25) = 17.5 cm.

Multiple choice
  1. $45$%
  2. $25$%
  3. $40$%
  4. $50$%
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Cutting the painted cube into two equal cuboids exposes one new square face on each solid. Each cuboid has total surface area 4s^2, while the unpainted face has area s^2, giving 1/4 or 25%.

Multiple choice
  1. $7$
  2. $5$
  3. $3$
  4. $8$
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice
  1. $10\ cm$
  2. $5\ cm$
  3. $15\ cm$
  4. $7\ cm$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice
  1. $300 cm^3$
  2. $600 cm^3$
  3. $150 cm^3$
  4. $450 cm^3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The cube floats, so the buoyant force equals the weight of the cube (700g). The volume of water displaced is 700 cm^3 (since density of water is 1g/cm^3). Total volume of the cube is 10*10*10 = 1000 cm^3. Volume outside water = Total volume - Displaced volume = 1000 - 700 = 300 cm^3.

Multiple choice
  1. $12\ sq. cm$
  2. $3\ sq. cm$
  3. $6\ sq. cm$
  4. $5\ sq. cm$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

For a right triangle, the hypotenuse is twice the circumradius, so its length is 6 cm. The area is 1/2 x hypotenuse x altitude to the hypotenuse = 1/2 x 6 x 2 = 6 square centimetres.