## Chapter 32 – Statistics Exercise Ex. 32.1

Calculate the mean deviation on the following income

groups of five and seven members from their medians:

I Income in Rs. | II income in Rs. |

4000 | 3800 |

4200 | 4000 |

4400 | 4200 |

4600 | 4400 |

4800 | 4600 |

4800 | |

5800 |

Note: Answer given in the book is

incorrect.

Calculate the mean deviation about the mean of the following data:

(v) 57, 64, 43, 67, 49, 59, 44, 47, 61, 59

## Chapter 32 – Statistics Exercise Ex. 32.2

Find the mean deviation from the mean for the following

data:

Size: | 1 3 5 7 9 11 13 15 |

Frequency: | 3 3 4 14 7 4 3 4 |

Find the mean deviation from the median for the

following data:

x | 15 21 27 30 |

f | 3 5 6 7 |

Note: Answer given in the book is

incorrect.

## Chapter 32 – Statistics Exercise Ex. 32.3

Calculate mean deviation about median age for the age

distribution of 100 persons given below:

Age: | 16-20 | 21-25 | 26-30 | 31-35 | 36-40 | 41-45 | 45-50 | 50-55 |

Number of persons | 5 | 6 | 12 | 14 | 26 | 12 | 16 | 9 |

## Chapter 32 – Statistics Exercise Ex. 32.4

Show that the two formulae for the standard deviation

of ungrouped data

Find the mean, variance and standard deviation for the data:

6, 7, 10, 12, 13, 4, 8, 12.

## Chapter 32 – Statistics Exercise Ex. 32.6

Calculate mean, variance

and standard deviation of the following frequency distribution:

Class: | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 |

Frequency: | 11 | 29 | 18 | 4 | 5 | 3 |

Find the mean and variance of frequency distribution

given below:

x | 1x <3 | 3 x<5 | 5x<7 | 7x<9 |

F | 6 | 4 | 5 | 1 |

Note: Answer given in the book is

incorrect.

Calculate the Mean, median and Standard Deviation of the following distribution:

Mean and standard deviation of 100 observation were found to be 40 and 10 respectively. If at the time of calculation two observations were wrongly taken as 30 and 70 in place of 3 and 27 respectively, find the correct standard deviation.

While calculating the mean and variance of 10 readings , a student wrongly used the reading of 52 for the correct reading 25. He obtained the mean and variance as 45 and 16 respectively. Find the correct mean and the variance.

## Chapter 32 – Statistics Exercise Ex. 32.7

Life of bulbs product by two factories A and B are

given below:

Length of life (in hours): Factory A: | 550-650 650-750 750-850 850-950 950-1050 |

(Number of bulbs) Factor B: | 10 22 52 20 16 |

(Number of bulbs) | 8 60 24 15 12 |

The bulbs of which factory are more consistent from the

point of view of length of life?

Following are mark obtained, out of 100, by two

students Ravi and Hashina in 10 tests:

Ravi: | 25 50 45 30 70 42 36 48 35 60 |

Hashina: | 10 70 50 20 95 55 42 60 48 80 |

Who is more intelligent and who is more consistent?

We observe that the average monthly wages in both firms is same i.e. Rs. 2500. Therefore the plant with greater variance will have greater variability. Thus plant B has greater variability in individual wages.

## Chapter 32 – Statistics Exercise Ex. 32.5

(i)

(ii)

(ii)

## Chapter 32 – Statistics Exercise Ex. 32VSAQ

New SD is