# Class 9 – Statistics – Important Questions

Important Questions**Statistics – Important Questions**

**Mean of 20 observations is 17. If in the observations, observation 40 is replaced by 12, find the new mean****What is the mean of first 10 natural numbers?****The mean of 100 observations is 50. If one of the observation which was 50 is replaced by 150 then what will be the resulting mean?****The number of family members in 10 flats of a society are****2, 4, 3, 3, 1, 0, 2, 4, 1, 5.****Find the mean number of family members per flat.****If the mean of 6, 8, 9, x, 13 is, find the value of x,****A cricketer has a mean score of 58 runs in nine innings. Find out how many runs are to be scored by him in the tenth innings to raise the mean score to 61.****The mean weight of a class of 34 students is 46.5 kg. If the weight of the new boy is included, the mean is rises by 500 g. Find the weight of the new boy.****The weight (in kg) of 7 students of a class are 44, 52, 55, 60, 50, 49, 45.****Find the median weight.****The width of each of five continuous classes in a frequency distribution is 5 and the lower class limit of the lowest class is 10. What is the upper class limit of the highest class?****The following data given the weight (in grams) of 30 oranges picked from a basket:****106 107 76 109 187 95 125 92 70****139 128 100 88 84 99 113 204 141****136 123 90 115 110 97 90 107 75****80 118 82****Construct a grouped frequency distribution table taking class width equal to 20 in such a way that the mid-value of first class in 70.****From the frequency table, find the number of oranges****weighing more than 180 g.****less than 100 g.**

**The blood groups of 30 students of Class VIII are recorded as follows:**

A, B, O, O, AB, O, A, O, B, A, O, B, A, O, O,

A, AB, O, A, A, O, O, AB, B, A, O, B, A, B, O.**Given below are the seats won by different political parties in the polling outcome of a state assembly elections:**

Political party | A | B | C | D | E | F |

Seats won | 75 | 55 | 37 | 29 | 10 | 37 |

**(i) Draw a bar graph to represent the polling results.(ii) Which political party won the maximum number of seats?**

**13.** **A teacher wanted to analyse the performance of two sections of students in a mathematics test of 100 marks. Looking at their performances, she found that a few students got under 20 marks and a few got 70 marks or above. So she decided to group them into intervals of varying sizes as follows: 0 – 20, 20 – 30, . . ., 60 – 70, 70 – 100. Then she formed the following table:**

Marks | Number of students |

0 – 20 | 7 |

20 – 30 | 10 |

30 – 40 | 10 |

40 – 50 | 20 |

50 – 60 | 20 |

60 – 70 | 15 |

70 – above | 8 |

Total | 90 |

**Draw a histogram to represent the given data.**

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