Calculate the mean and standard deviation for the following distribution: Marks:, 20-30, 30-40, 40-50, 50-60, 60-70, 70-80, 80-90 No. of students:, 3, 6, 13, 15, 14, 5, 4

Explanation

Table for mean and standard deviation is given below

`[[class],[20-30],[30-40],[40-50],[50-60],[60-70],[70-80],[80-90]]`
`[[f],[3],[6],[13],[15],[14],[5],[4]]`
`[[x],[25],[35],[45],[55],[65],[75],[85]]`
`[[u],[-3],[-2],[-1],[0],[1],[2],[3]]`
`[[u^2],[9],[4],[1],[0],[1],[4],[9]]`
`[[fu],[-9],[-12],[-13],[0],[14],[10],[12]]`
`[[fu^2],[27],[24],[13],[0],[14],[20],[36]]`
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