# IMO Level 1- Mathematics Olympiad (SOF) Class 10: Questions 639 - 646 of 968

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## Question 639

### Question

MCQ▾If ‘a’ is the A. M. of 3 numbers and ‘b’ is the A. M. of their squares, then the A. M. of their pair-wise products in terms of a and b is ________

### Choices

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

a. | ||

b. | ||

c. | ||

d. |

## Question 640

### Question

MCQ▾The value of is ________

### Choices

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

a. | 420 | |

b. | 210 | |

c. | 195 | |

d. | 390 |

## Question 641

### Question

MCQ▾If four numbers are in A. P. such that their sum is 90 and the greatest number is 4 times the least, then the numbers are ________

### Choices

Choice (4) | Response | |
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a. | ||

b. | ||

c. | ||

d. | Question does not provide sufficient data or is vague |

## Question 642

### Question

MCQ▾Between the numbers 7 and 70,28 means are inserted, then their sum is ________

### Choices

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

a. | 1795 | |

b. | 1078 | |

c. | 1695 | |

d. | 1895 |

## Question 643

### Question

MCQ▾In an A. P, If it is given that then is equal to ________

### Choices

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

a. | ||

b. | ||

c. | ||

d. |

## Question 644

## Question 645

### Question

MCQ▾If up to n terms and n is even, then S equals________

### Choices

Choice (4) | Response | |
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a. | ||

b. | ||

c. | ||

d. |

## Question 646

### Question

MCQ▾Let denotes the sum of n terms of an A. P. , whose first term is a. if the common difference d is given by then K is equal to ________ ________

### Choices

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

a. | 4 | |

b. | 1 | |

c. | 3 | |

d. | 2 |