# Surface Area and Volumes (IMO- Mathematics Olympiad Class 9): Questions 72 - 77 of 104

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## Question number: 72

» Surface Area and Volumes

MCQ▾

### Question

What change in percent is made in the area of a rectangle by decreasing its length and increasing its breadth by ?

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 73

» Surface Area and Volumes

MCQ▾

### Question

The heights of two cones are in the ratio of 3: 8 and their radius in the ratio 5: 3. Then the ratio of their volumes is ________

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 74

» Surface Area and Volumes

MCQ▾

### Question

The area of rhombus is and one of its diagonals is 8 cm. its perimeter is ________

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 75

» Surface Area and Volumes

MCQ▾

### Question

The largest sphere is cut off from a cube of side 8 cm. the volume of the sphere will be ________

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 76

» Surface Area and Volumes

MCQ▾

### Question

A spherical ball of lead, 9 cm in diameter is melted and recast into four spherical balls. The diameter of three of these are 3 cm, 2 cm, 2.5 cm is respectively. The radius of the fourth ball is________.

### Choices

Choice (4) Response

a.

8.79 cm

b.

6.79 cm

c.

7.79cm

d.

5.79 cm

## Question number: 77

» Surface Area and Volumes

MCQ▾

### Question

A cylindrical rod whose height is 12 times of its radius is melted and recast into spherical balls of same radius. The numbers of balls will be________

### Choices

Choice (4) Response

a.

9

b.

2

c.

7

d.

6

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