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:

Weights of Coffee in 70 Jars
Weights of Coffee in 70 jars

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

The Weights of Coffee in 70 Jars
The weights of coffee in 70 jars

Weight (in grams)

Mid Value

Frequency

Total

Here mean,

So the above table with more columns is as shown below,

The Above Table with More Columns
The above table with more columns

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.

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