Math, asked by BrainlyHelper, 1 year ago

Question 4 Find the mean and variance for the data




xi 6 10 14 18 24 28 30

f i 2 4 7 12 8 4 3

Class X1 - Maths -Statistics Page 371

Answers

Answered by abhi178
5
see attachment ,
we get,
\sum{f_i}=40\\\\\sum{f_ix_i}=760\\\\\sum{f_ix_i^2}=16176
so,
Mean(\overline{x})=\frac{\sum{f_ix_i}}{\sum{f_i}}\\\\=\frac{760}{40}=19\\\\\\NOW, variance=\frac{\sum{f_ix_i^2}}{\sum{f_i}}-[\frac{\sum{f_ix_i}}{\sum{f_i}}]^2\\\\=\frac{16176}{40}-[\frac{760}{40}]^2\\\\=404.4-(19)^2\\\\=404.4-361=43.4
hence, answer is 43.4
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