# IMO Level 1- Mathematics Olympiad (SOF) Class 9: Questions 820 - 825 of 929

Access detailed explanations (illustrated with images and videos) to 929 questions. Access all new questions we will add tracking exam-pattern and syllabus changes. Subscription can be renewed yearly absolutely FREE! View Sample Explanation or View Features.

Rs. 450.00 or

How to register?

## Question number: 820

Edit
MCQ▾

### Question

A group of 1200 persons consisting of captains and soldiers is travelling in a train. For every 15 soldiers there is one captain. The number of captains in the group is

### Choices

Choice (4) Response

a.

80

b.

70

c.

75

d.

85

## Question number: 821

Edit
MCQ▾

### Question

In a class test, in mathematics, 10 students scored 75 marks, 12 students scored 60 marks, 8 scored 40 marks and 3 scored 30 marks. The mean of their score is (approximately) ________

### Choices

Choice (4) Response

a.

57 marks

b.

15 marks

c.

56 marks

d.

54 marks

## Question number: 822

Edit
MCQ▾

### Question

Tea worth Rs. 126 per kg and Rs. 135 per kg are mixed with a third variety in the ratio. If the mixture is worth Rs. 153 per kg, the price of the third variety per kg will be

### Choices

Choice (4) Response

a.

Rs. 169.50

b.

Rs. 180

c.

Rs. 175.50

d.

Rs. 170

## Question number: 823

Edit
MCQ▾

Factors of

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 824

Edit
MCQ▾

### Question

If 3 is added to the denominator of a fraction, the fraction becomes 6. If 4 is added to the numerator, the fraction becomes 30, the fraction is ________.

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 825

Edit
MCQ▾

### Question

A box contains 8 balls out of which x are black. If one ball is drawn at random from the box, what is the probability that it will be a black ball? If 4 more black balls are put in the box, the probability of drawing a black ball is now double of what is was before, then x is________

### Choices

Choice (4) Response

a.

6

b.

3

c.

9

d.

2