Home
Class 11
MATHS
the mean and standard deviation of some ...

the mean and standard deviation of some data for the time taken to complete a test are calculated with the following results:
Number of observations = 25, mean = 18.2 seconds , standard deviation = 3.25 seconds. Further , another set of 15 observations `x_1,x_2,........,x_15`, also in seconds , is now available and we have `sum_(i=1)^15 x_i = 279` and `sum_(i=1)^15 x_i^2 = 5524. `
Calculated the standard deviation based on all 40 observations.

Text Solution

Verified by Experts

The correct Answer is:
3.87
Promotional Banner

Topper's Solved these Questions

  • STATISTICS

    KUMAR PRAKASHAN|Exercise NCERT EXEMPLAR PROBLEMS (OBJECTIVE TYPE QUESTIONS)|16 Videos

  • STATISTICS

    KUMAR PRAKASHAN|Exercise NCERT EXEMPLAR PROBLEMS (FILLERS)|6 Videos

  • STATISTICS

    KUMAR PRAKASHAN|Exercise TEXTBOOK ILLUSTRATIONS FOR PRACTICE WORK|19 Videos

  • SETS

    KUMAR PRAKASHAN|Exercise QUESTION OF MODULE|28 Videos

  • STRAIGHT LINES

    KUMAR PRAKASHAN|Exercise Question of Module (Knowledge Test :)|18 Videos

Similar Questions

Explore conceptually related problems

If sum_(i=1)^9 (x_i - 5) = 9 and sum_(i=1)^9 (x_i - 5)^2 = 45. The standard deviation of the observations x_1, x_2,………,x_9 is ………….

The standard deviation is …….to the mean deviation taken from the arithmetic mean.

Calculate the mean deviation about median for the following data :

The mean and standard deviation of a random variable X are 10 and 5 respectively. Match the following.

The mean of 100 observations is 50 and their standard deviation is 5. The sum of all squares of all the observations is ………….

Determine the mean and standard deviation for the following distribution:

Let x_1,x_2, x_3, x_4, x_5 be the observations with mean m and standard deviation S. The standard deviation of the observations kx_1,kx_2,kx_3,kx_4,kx_5 is ……….

The mean and standard deviation of random variable X are 10 and 5 respectively, then E((X-15)/(5))^(2)= ____

Mean deviation for n observation x_1,x_2,……….,x_n from their mean barx is given by …….

KUMAR PRAKASHAN-STATISTICS-NCERT EXEMPLAR PROBLEMS (SHORT ANSWER TYPE QUESTIONS)
  1. Find the algebraic sum of the deviations of all the observations from ...

    Text Solution

    |

  2. Find the standard deviation of the first n natural numbers.

    Text Solution

    |

  3. the mean and standard deviation of some data for the time taken to com...

    Text Solution

    |

  4. Mean and standard deviation of the random variable X are (7)/(3) and (...

    Text Solution

    |

  5. Two sets each of 20 observations , have the same standard deviation 5....

    Text Solution

    |

  6. The frequency distribution : Where A is a positive integer , ha...

    Text Solution

    |

  7. For the frequency distribution: Find the standard distribution ...

    Text Solution

    |

  8. There are 60 students in a class . The following is the frequency dist...

    Text Solution

    |

  9. The mean life of a sample of 60 bulbs was 650 hours and the standard d...

    Text Solution

    |

  10. Mean and standard deviation of 100 items are 50 and 4, respectively . ...

    Text Solution

    |

  11. If for a distribution sum(x-5) = 3, sum(x - 5)^2 = 43 and the total nu...

    Text Solution

    |

  12. Find the mean variance of the frequency distribution given below :

    Text Solution

    |

  13. Calcualte the mean deviation about the mean for the following frequenc...

    Text Solution

    |

  14. Calcualte the mean deviation from the median of the following data :

    Text Solution

    |

  15. Determine the mean and standard deviation for the following distributi...

    Text Solution

    |

  16. The weights of coffee in 70 jars is shown in the following table: ...

    Text Solution

    |

  17. Determine mean and standard deviation of first n terms of an A.P. whos...

    Text Solution

    |

  18. Following are the marks obtained , out of 100 by two students ravi and...

    Text Solution

    |

  19. Mean and standard deviation of 100 observations were found to be 40 an...

    Text Solution

    |

  20. While calculating the mean and variance of 10 readings, a student wron...

    Text Solution

    |