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The mean life of a sample of 60 bulbs wa...

The mean life of a sample of 60 bulbs was 650 hours and the standard deviation was 8 hours. A second sample of 80 bulbs has mean life of 660 hours standard deviation 7 hours . Find the overall standard deviation.

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8.9
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KUMAR PRAKASHAN-STATISTICS-NCERT EXEMPLAR PROBLEMS (SHORT ANSWER TYPE QUESTIONS)
  1. Find the algebraic sum of the deviations of all the observations from ...

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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