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CLASS_11_MATHS_SOLUTIONS_NCERT

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Class XI Chapter 15 – Statistics Maths<br />

______________________________________________________________________________<br />

∴ Standard deviation of the distribution of wages in firm<br />

A ((σ1) = 100 10<br />

2<br />

Variance of the distribution of wages in firm B 2 = 121<br />

2<br />

∴ Standard deviation of the distribution of wages in firm 2 <br />

B 121 <strong>11</strong><br />

The mean of monthly wages of both the firms is same i.e., 5253. Therefore, the firm with greater<br />

standard deviation will have more variability.<br />

Thus, firm B has greater variability in the individual wages.<br />

Question 4:<br />

The following is the record of goals scored by team A in a football session:<br />

No. of goals 0 1 2 3 4<br />

scored<br />

No. of 1 9 7 5 3<br />

matches<br />

For the team B, mean number of goals scored per match was 2 with a standard<br />

deviation 1.25 goals. Find which team may be considered more consistent?<br />

Solution 4:<br />

The mean and the standard deviation of goals scored by team A are calculated as follows.<br />

No. of goals No. of matches<br />

2<br />

2<br />

fi<br />

x<br />

i<br />

x<br />

i<br />

fi<br />

x<br />

i<br />

scored<br />

0 1 0 0 0<br />

1 9 9 1 9<br />

2 7 14 4 28<br />

3 5 15 9 45<br />

4 3 12 16 48<br />

25 50 130<br />

15<br />

50<br />

Mean= fixi<br />

2<br />

i1<br />

25<br />

Thus, the mean of both the teams is same.<br />

1 2<br />

N f 2<br />

i x<br />

i<br />

f<br />

i x<br />

i<br />

N<br />

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