# 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 |