NCERT Class 11-Math's: Exemplar Chapter –15 Statistics Part 7
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Question 19:
The weights of coffee in jars is shown in the following table:
Weight (in grams) | Frequency |
200-201 | 13 |
201-202 | 27 |
202-203 | 18 |
203-204 | 10 |
204-205 | 1 |
205-206 | 1 |
Determine variance and standard deviation of the above distribution.
Answer:
Given: the weights of coffee in 70 jars
To find: the variance and standard deviation of the distribution
Let us make a table of the given data and append other columns after calculations
Weight (in grams) | Mid Value | Frequency | |
Total |
Here mean,
So the above table with more columns is as shown below,
Weight (in grams) | Mid Value | Frequency | |||
Total |
And we know standard deviation is
Substituting values from above table, we get
And
Hence the variance and standard deviation of the distribution are 1.166g and 1.08 respectively.