Q10 of 46 Page 278

For the frequency distribution:


Find the standard distribution.

Given: frequency distribution table


To find: the standard deviation


Let us make a table of the given data and append other columns after calculations



And we know standard deviation is



Substituting values from above table, we get





⇒ σ=1.37


Hence the standard deviation is 1.37.


More from this chapter

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Two sets each of 20 observations, have the same standard derivation 5. The first set has a mean 17 and the second a mean 22. Determine the standard deviation of the set obtained by combining the given two sets.

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The frequency distribution:


where A is a positive integer, has a variance of 160. Determine the value of A.

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There are 60 students in a class. The following is the frequency distribution of the marks obtained by the students in a test:


where x is a positive integer. Determine the mean and standard deviation of the marks.

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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 a mean life of 660 hours and standard deviation 7 hours. Find the overall standard deviation.