# IMO- Mathematics Olympiad Class 8: Questions 570 - 576 of 1029

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## Question number: 570

» Direct and Inverse Proportions

### Question

If 4 men take an hour to dig a ditch, how long should it take 10 men to dig a ditch of the same type?

### Choices

Choice (4) | Response | |
---|---|---|

a. | 20 min | |

b. | 23 min | |

c. | 24 min | |

d. | 30 min |

## Question number: 571

### Question

Number of prime factors in is

### Choices

Choice (4) | Response | |
---|---|---|

a. | 20 | |

b. | 28 | |

c. | 23 | |

d. | 22 |

## Question number: 572

» Direct and Inverse Proportions

### Question

If A: B = 3: 4 and B: C = 5: 6, then C: A is equal to, ________.

### Choices

Choice (4) | Response | |
---|---|---|

a. | 15: 14 | |

b. | 24: 15 | |

c. | 12: 23 | |

d. | 25: 14 |

## Question number: 573

### Question

The value of when is________.

### Choices

Choice (4) | Response | |
---|---|---|

a. | 80 | |

b. | 81 | |

c. | 85 | |

d. | 84 |

## Question number: 574

» Direct and Inverse Proportions

### Question

A cistern has two inlets A and B which can fill it in 10 minutes and 20 minutes respectively. An outlet C can empty the full cistern in 4 minutes. If all the pipes are opened together in the empty tank, time taken to fill the tank completely is ________.

### Choices

Choice (4) | Response | |
---|---|---|

a. | 25 minutes | |

b. | 20 minutes | |

c. | 15 minutes | |

d. | 10 minutes |

## Question number: 575

### Question

Number of prime factors in is

### Choices

Choice (4) | Response | |
---|---|---|

a. | 73 | |

b. | 60 | |

c. | 66 | |

d. | 70 |

## Question number: 576

» Direct and Inverse Proportions

### Question

A water tank is two-fifth full. Pipe A can fill a tank in 12 minutes and pipe B can empty it in 6 minutes. If both the pipes are open, how long will it take to empty or fill the tank completely?

### Choices

Choice (4) | Response | |
---|---|---|

a. | 4.8 minutes | |

b. | 5 minutes | |

c. | 4 minutes | |

d. | 5.5 minutes |