# IMO Level 1- Mathematics Olympiad (SOF) Class 10: Questions 513 - 518 of 968

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## Question 513

### Question

MCQ▾

5 bells commence tolling together and toll at intervals of 3, 6,9, 12 and 15 seconds respectively. In 12 minutes, how many times do they toll together?

### Choices

Choice (4)Response

a.

7

b.

4

c.

6

d.

5

## Question 514

### Question

MCQ▾

The present ages of A, B and C are in proportions . Eight years ago, the sum of their ages was 76. What are their present ages (in years) ?

### Choices

Choice (4)Response

a.

b.

c.

d.

## Question 515

### Question

MCQ▾

Kamla got married 6 years ago. Today her age is times her age at the time of marriage. Her son՚s age is times her age. Her son՚s age is ________

### Choices

Choice (4)Response

a.

3 years

b.

2 years

c.

5 years

d.

4 years

## Question 516

### Question

MCQ▾

2 men and 7 boys can do a piece of work in 14 day, 3 men and 8 boys can do the same in 11 days. 8 men and 6 boys can do 3 times the amount of this work in ________

### Choices

Choice (4)Response

a.

18 days

b.

21 days

c.

36 days

d.

24 days

## Question 517

### Question

MCQ▾

P is twice good a workman as Q and therefore is able to finish a job in 30 days less than Q. Working together they can do it in ________ days.

### Choices

Choice (4)Response

a.

50

b.

30

c.

20

d.

40

## Question 518

### Question

MCQ▾

28 integers are chosen from the interval [104,208] . Show that there exit two of them having a common prime divisor.

### Choices

Choice (4)Response

a.

1

b.

0

c.

3

d.

2