1.
If each edge of cube increased by 10%, the percentage increase in surface area is:
Answer: Option 'A'
100 × (110)/100 × (110)/100 × (110)/100 => 1331/100 = 33.1%
2.
The radius of a cone is 10 m, height 21 m. The volume of the cone is:
Answer: Option 'C'
1/3 πrh = 1/3 × 22/7 × 100 × 21
= 2200 m3
3.
Three cubes of sides 5 m, 4 m, and 3 m are melted to form a new cube. Find the surface of the new cube?
Answer: Option 'C'
Volume of the new cube = [ 53 + 43 + 33 ] Cm3
= 125 + 64 + 27 = 216 Cm3 => a3 = 216 Cm3
4.
The radius of hemi-sphere is 7 m. Find it's total surface area?
Answer: Option 'C'
otace area = 3πr2 sq.units
= 3 × 22/7 × 7 × 7
= 66 × 7 = 462 m3
5.
If the radius of sphere is doubled, then its volume is increased by:
Answer: Option 'C'
radius = r. Original volume = 4/3 πr3
New radius = 2r New volume = 4/3 π(2r)3 = (32πr3)/3
increase in volume = ( (32πr3)/3 × 3/(4πr3) × 100 ) % = 700%