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- Question
- If each edge of a cube is increased in increased by 50%, the percentage increase in surface area is?
Options- A. 50 %
- B. 75 %
- C. 100 %
- D. 125 %
- Correct Answer
- 125 %
ExplanationLet original length of cube = L
Then, its surface area = 6L2
New edge = (150 x L)/10 = 3L/2
New surface area = 6 x (3L/2)2 = (6 x 9 x L2)/4 = (27/2) x L2
Increase in surface area = (27/2 - 6) x L2 = 15 x L2/2
? Increase percent = (15 x L2/2 ) / (6L2) x 100 % = 125 % - 1. Two cubes have volumes in the ratio 1: 27, The ratio of their surface areas is?
Options- A. 1 : 3
- B. 1 : 8
- C. 1 : 9
- D. 1 : 18 Discuss
- 2. A tank 3 m long, 2 m wide and 1.5 m deep is dug in a field 22 m long and 14 m wide. If the earth dug out is evenly spread out over the field, the rose in level of the field will be?
Options- A. 0.299 cm
- B. 0.29 cm
- C. 2.98 cm
- D. 4.15 cm Discuss
- 3. A sphere of radius r has the same volume as that of a cone with circular base of radius r. Find the height of the cone.?
Options- A. 2r
- B. r/3
- C. 4r
- D. (2/3)r Discuss
- 4. Find the total surface area of a pyramid having a slant height of 8 cm and a base which is a square of side 4 cm (in cm 2)?
Options- A. 80
- B. 64
- C. 72
- D. 84 Discuss
- 5. A hemisphere has 3 cm radius. Calculate its volume.?
Options- A. 4/3 ? cm3
- B. 13 ? cm3
- C. 18? cm3
- D. 19/? cm3 Discuss
- 6. The difference in volumes of two cubes is 152 m 3 and the difference in their one face areas is 20 m 2. If the sum of their edge is 10 m, the product of their edge is?
Options- A. 21
- B. 24
- C. 36
- D. 48 Discuss
- 7. The sun of length, breadth and depth of a cuboid is 19 cm and its diagonal is 5 ? 5 cm. Its surface area is?
Options- A. 361 cm2
- B. 125 cm2
- C. 236 cm2
- D. 486 cm2 Discuss
- 8. A tank 30 m long, 20 m wide and 12 m deep is dug in a field 500 m long and 30 m wide. By how much will the level of the field rise, if the Earth dug of the tank is evenly spread over the field?
Options- A. 0.33 m
- B. 0.5 m
- C. 0.25 m
- D. 0.4 m Discuss
- 9. A right circular cone of height h is cut by a plane parallel to the base at a distance h/3 from the base, then the volumes of the resulting come and the frustum are in the ratio?
Options- A. 4/7
- B. 8/19
- C. 6/19
- D. 18/19 Discuss
- 10. If height of a cylinder is increased by 17.5 % while its radius remains unchanged, by what percent does its volume increase?
Options- A. 17.5%
- B. 18%
- C. 19.8%
- D. 25% Discuss
Volume and Surface Area problems
Search Results
Correct Answer: 1 : 9
Explanation:
Let the volume be x3 and 27x3
? Their edges are x and 3x
Now Ratio of their surface area = 6x2 : 54x2 = 1 : 9
Correct Answer: 2.98 cm
Explanation:
Earth dug out = (3 x 2 x 1.5 ) m3 = 9 m3
Area on which earth has been spread = (22 x 14 - 3 x 2 ) m2 = 302 m2
? Rise in level = Volume/Area = (9/302) m = (9 x 100/302) cm = 2.98 cm
Correct Answer: 4r
Explanation:
Given that,
Volume of sphere = Volume of cone
? (4/3)?r3 = (1/3)?r2h
? 4r = h
Correct Answer: 80
Explanation:
Total surface area of the pyramid
= [1/2(perimeter of the base) (Slant height) ] + Area of the base
= 1/2 (4) (4) (8) + 42 = 80 cm2
Correct Answer: 18? cm3
Explanation:
volume = (2/3)?r3
= (2/3) x ? x 33
= (2/3) x ? x 27
= 18? cm3
Correct Answer: 24
Explanation:
Let the edges of the two cubes be x and y metres
Then, x3 - y3 = 152
and x2 - y2 = 20
Also, x + y = 10
So, x - y = (x2 - y2) / (x + y) = 20/10 = 2
Now, (x3 - y3) / (x - y) = 152/2
? x2 + y2 + xy = 76
? (x + y)2 - xy = 76
? xy = (x + y)2 - 76 = (10)2 - 76 = 24
Correct Answer: 236 cm2
Explanation:
? l + b + h = 19
and l2 + b2 + h2 = (5?5)2 = 125
? (l + b + h)2 = (19)2
? (l2 + b2+ h2) + 2(lb + bh + lh) = 361
? 2 (lb + bh + lh) = (361 - 125) = 236
? Surface area = 236 cm2
Correct Answer: 0.5 m
Explanation:
Volume of the Earth taken out = 30 x 20 x 12
= 7200 m3
Area of the remaining portion (leaving the area of dug out portion) = 470 x 30 + 30 x 10
= 14100 + 300 = 14400 m3
Let h be height to which the field is raised by spreading the Earth dug out.
Then, 14400 x h = 7200
? h = 7200/14400 = 0.5 m
Correct Answer: 8/19
Explanation:
The volume of the original cone is V = (?R2h)/3
The height and the radius of the smaller cone are 2h/3 and 2R/3, respectively
? 1/3? (2R/3)2 x 2h/3 = 8V/27
? Volume of the frustum = (V - 8V/27) = 19V/27
So, the required ratio is 8 : 19 .
Correct Answer: 25%
Explanation:
If the radius remains unchanged
Then, x = y = 0 and z = 17.5 %
? Net increase in volume = 17.5%
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