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Practice Questions

:- You can add tough questions into
your favourite list for second revision. Note |

Q1. | The average of first 50 natural numbers is : |

A. | 12.25 [Wrong Answer] |

B. | 21.25 [Wrong Answer] |

C. | 25 [Wrong Answer] |

D. | 25.5 [Correct Answer] |

View Answer
Explanation:-
Answer : DDiscuss it below :Sum of first n natural numbers = ^{n (n + 1)}/_{2}So, average of first n natural numbers = ^{n (n + 1)}/_{2n}^{n + 1}/_{2}∴ Required average = ^{50 + 1}/_{2}^{51}/_{2}Click here for more comments |

Q2. | The average of first five multipies of 3 is : |

A. | 3 [Correct Answer] |

B. | 9 [Wrong Answer] |

C. | 12 [Wrong Answer] |

D. | 15 [Wrong Answer] |

View Answer
Explanation:-
Answer : ADiscuss it below :Average =
^{3 (1 + 2 + 3 + 4 + 5)}/_{5}= ^{45}/_{5}Click here for more comments |

Q3. | A library has an average of 510 visitors on Sundays and 240 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is : |

A. | 250 [Wrong Answer] |

B. | 276 [Wrong Answer] |

C. | 280 [Wrong Answer] |

D. | 285 [Correct Answer] |

View Answer
Explanation:-
Answer : DDiscuss it below :Since the month begins with a Sunday so there will be five Sundays in the month.∴ Required average = ^{510x 5 +240 x 25}/_{30}^{8550}/_{30}Click here for more comments |

Q4. | If the arithmetic mean of seventy-five numbers is calculated, it is 35. If each number is increased by 5, then mean of new numbers is : |

A. | 30 [Wrong Answer] |

B. | 40 [Correct Answer] |

C. | 70 [Wrong Answer] |

D. | 90 [Wrong Answer] |

View Answer
Explanation:-
Answer : BDiscuss it below :A.M. of 75 numbers = 35.Sum of 75 numbers = (75 x 35) = 2625. Total increase = (75 x 5) = 375. Increased sum = (2625 + 375) = 3000. Increased average = ^{3000}/_{75}Click here for more comments |

Q5. | The sum of three consecutive odd numbers is 38 more than the average of these numbers. What is the first of these numbers ? |

A. | 13 [Wrong Answer] |

B. | 17 [Correct Answer] |

C. | Data inadequate [Wrong Answer] |

D. | None of these [Wrong Answer] |

View Answer
Explanation:-
Answer : BDiscuss it below :Let the numbers be x, x + 2 and x + 4.Then, (x + x + 2 + x + 4) - ^{(x+x+2+x+4)}/_{3}or (3x + 6) - ^{(3x + 6)}/_{3}or 2 (3x + 6) = 114 or 6x = 102 or x = 17. So, first number = x = 17. Click here for more comments |

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