The table alongside summarises the examination scores for 80 randomly selected students

MATHEMATICS · Subjective · CBSE · Mathematics · Statistics · Statistics

Problem

The table alongside summarises the examination scores for 80 randomly selected students. Estimate the standard deviation for the data.
MarkFrequencyMarkFrequency
0 - 9150 - 5916
10 - 19160 - 6924
20 - 29270 - 7913
30 - 39480 - 896
40 - 491190 - 992
Class intervalMid-interval valueFrequency
0 - 94.51
10 - 1914.51
20 - 2924.52
30 - 3934.54
40 - 4944.511
50 - 5954.516
60 - 6964.524
70 - 7974.513
80 - 8984.56
90 - 9994.52
For continuous data or data grouped in classes, use the mid-interval value to represent all data in that interval.

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