Measures of Dispersion
Important Questions on Measures of Dispersion
The mean of observations is and the variance is . If three of the five observations are and , find the other two observations.

Following data gives age of students in a college. Calculate variance and S.D.
Age(In year) | 16 | 17 | 18 | 19 | 20 | 21 |
No. of student | 20 | 7 | 11 | 17 | 30 | 15 |

Compute the variance and S.D.
Frequency |

Compute variance and standard deviation for the following data:

Find variance and S.D. for the following set of numbers.

Find variance and S.D. for the following set of numbers.

Compute coefficient of variation for team A and team B.
No. of goals | 0 | 1 | 2 | 3 | 4 |
No. of matches played by team A | 19 | 6 | 5 | 16 | 14 |
No. of matches played by team B | 16 | 14 | 10 | 14 | 16 |

The following table gives weights of the students of two classes. Calculate the coefficient of variation of the two distributions. Which series is more variable?
Weight (in kg) | Class A | Class B |
30-40 | 22 | 13 |
40-50 | 16 | 10 |
50-60 | 12 | 17 |

The standard deviation of a distribution divided by the mean of the distribution and expressing in percentage is called:

If the observations of a variable are, and , then the value of the range will be:

Given below is the information about marks obtained in Mathematics and Statistics by students in a class. If the coefficient of variation of the subject showing the highest variability in marks is then find the value of .
Mathematics | statistics | |
Mean | ||
S.D. |

A group of students of class XI have their average height is cm with coefficient of variance . What is the standard deviation of their height(in cm)?

Calculate coefficient of variation correct up to second decimal place of marks secured by a student in the exam, where the marks are:

For a certain data, following information is available.
X | Y | |
Mean | 13 | 17 |
S.D. | 3 | 2 |
Size | 20 | 30 |
Obtain the combined standard deviation rounding off upto second decimal places.

The means of two samples of sizes and respectively are and and the standard deviations and . Obtain the standard deviation of the sample of size obtained by combining the two sample correct upto two decimal places.

Find range for the following data.
Classes | |||||
Frequency |

Following results were obtained by rolling a die times. Find the range of the data.
Score | 1 | 2 | 3 | 4 | 5 | 6 |
Frequency | 4 | 6 | 2 | 7 | 3 | 3 |

The following data gives the number of typing mistakes done by Radha during a week. Find the range of the data.
Day | Monday | Tuesday | Wednesday | Thursday | Friday | Saturday |
Number of mistakes |

Find the range of the following data:
.

Find the range of the following data:
.

