Discussion
Home ‣ Aptitude ‣ Volume and Surface Area Comments
- Question
- If the radius of a sphere is increased by 3%, then what percent increase takes place in surface area of the sphere?
Options- A. 6.09%
- B. 7%
- C. 5.06%
- D. 9%
- Correct Answer
- 6.09%
ExplanationAccording to the formula
Percentage increase in surface area = [ 2x + x2/100]%
= [2 x 3 + (3)2/100]%
= [6 + 0.09]%
= 6.09% - 1. A metallic sphere of radius 12 cm is melted into three smaller spheres. If the radii of two smaller spheres are 6 cm and 8 cm, the radius of the third is?
Options- A. 14 cm
- B. 16 cm
- C. 10 cm
- D. 12 cm Discuss
- 2. What will be the difference between total surface area and curved surface area of a hemisphere having 2 cm diameter?
Options- A. 2? sq cm
- B. 3? sq cm
- C. ? sq cm
- D. 4? sq cm Discuss
- 3. A hemisphere has 28 cm diameter. Find its curved surface area.?
Options- A. 1232 sq cm
- B. 1236 sq cm
- C. 1238 sq cm
- D. 1233 sq cm Discuss
- 4. If 64 identical small spheres are made out of a big sphere of diameter 8 cm, what is surface area of each small sphere?
Options- A. ? cm2
- B. 2 ? cm2
- C. 4 ? cm2
- D. 8 ? cm2 Discuss
- 5. If the ratio of the diameters of two spheres is 3: 5, then what is the ratio of their surface areas?
Options- A. 9 : 25
- B. 9 : 10
- C. 3 : 5
- D. 27 : 125 Discuss
- 6. If radius of a sphere is decreased by 24%, by what per cent does its surface area decrease?
Options- A. 44%
- B. 49%
- C. 42.24%
- D. 46.2% Discuss
- 7. If the radius of a sphere is increased by 100%, by what per cent does its volume increase?
Options- A. 300%
- B. 900%
- C. 500%
- D. 700% Discuss
- 8. Weight of a solid metallic sphere of radius 4 cm is 4 kg. The weight of a hollow sphere made with same metal, whose outer diameter is 16 cm and inner diameter is 12 cm, is?
Options- A. 20.5 kg
- B. 15.5 kg
- C. 16.5 kg
- D. 18.5 kg Discuss
- 9. A prism has the base a right angled triangle whose sides adjacent to the right angle are 10 cm and 12 cm long. The height of the prism is 20 cm. The density of the material of the prism is 6 g/cu cm. The weight of the prism is?
Options- A. 3.4 kg
- B. 4.8 kg
- C. 6.4 kg
- D. 7.2 kg Discuss
- 10. The perimeter of the triangular base of a right prism is 60 cm and the sides of the base are in the ratio 5 : 12 : 13. Then, its volume will be (height of the prism being 60 cm).?
Options- A. 6000 cm3
- B. 6600 cm3
- C. 5400 cm3
- D. 9600 cm3 Discuss
Volume and Surface Area problems
Search Results
Correct Answer: 10 cm
Explanation:
Let radius of the third sphere be r.
Then, 4/3 ? x (12)3 = 4/3 ? x (6)3 + 4/3? x (8)3 + 4/3 ?r3
? (12)3 = (6)3 + (8)3 + r3
? r3 = 1728 - 216 - 512
? r3 = 1000
? r = 10 cm
Correct Answer: ? sq cm
Explanation:
Given,
Diameter = 2 cm
? r = 1 cm
Now, Total surface area of hemisphere = 3?r2
and curved surface area = 2?r2
Required difference = 3?r2 - 2?r2 = ?r2
= ? x 12 = ? sq cm
Correct Answer: 1232 sq cm
Explanation:
Curved surface area = 2?r2
= 2? x 14 x 14 = 2 x (22/7) x 14 x 14
= 2 x 22 x 2 x 14
= 88 x 14
= 1232 sq cm
Correct Answer: 4 ? cm2
Explanation:
Volume of small spheres
= Volume of bigger sphere / Number of small spheres = [(4/3)?(4)3] / 64
= [(4/3) x ? x 4 x 4 x 4] / 64
= 4/3 ? cm3
Let radius of small sphere be r
? 4/3?r3 = 4?/3
? r2 = 1 cm
Now, surface area of small sphere = 4?r2 = 4? cm2
Correct Answer: 9 : 25
Explanation:
Let the diameter's of two sphere are d1 and d2, respectively.
? Ratio of their surface areas = 4?r12/4?r22
= (2r1)2/(2r2)2 = d12/d22
= (d1/d2)2 = (3/5)2 = 9/25 = 9 : 25
Correct Answer: 42.24%
Explanation:
According to the formula,
Percentage decrease in surface area = [2 x (-24) + (-24) x (-24)/100]%
= [-48 + 5.76]% = - 42.24%
Correct Answer: 700%
Explanation:
Here, n = 100%
According to the formula
Percentage increase in volume = [(1 + n/100)3 - 1] x 100%
= [(1 + 100/100)3 - 1] x 100%
= [8 - 1] x 100% = 700%
Correct Answer: 18.5 kg
Explanation:
Volume of solid sphere of radius 4 cm = (4/3)?(4)3 cm3
Volume of hollow sphere = 4/3?[(8)3 - (6)3] cm3
? Weight of 4/3?(4)3 cm3 = 4 kg
= 4(512 - 216)/43 = 18.5 kg
Correct Answer: 7.2 kg
Explanation:
Volume of prism = Area of base x Height
= (1/2) x 10 x 12 x 20
= 1200 cm2
? Weight of prism = 1200 x 6
= 7200 g
= 7.2 kg
Correct Answer: 6000 cm3
Explanation:
Let the sides of the base are 5k, 12k and 13k, respectively.
Given, perimeter of base = 60 cm
? 5k + 12k + 13k = 60
? k = 60/30 = 2
The sides of base are 10 cm, 24 cm 26 cm.
? Volume of prism = (1/2) x 10 x 24 x 50 = 6000 cm3
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