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CLASS_11_MATHS_SOLUTIONS_NCERT

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Class XI Chapter 15 – Statistics Maths<br />

______________________________________________________________________________<br />

1 25130 50 2<br />

25<br />

1<br />

750<br />

25<br />

1<br />

27.38<br />

25<br />

1.09<br />

The standard deviation of team B is 1.25 goals.<br />

The average number of goals scored by both the teams is same i.e., 2. Therefore, the team with<br />

lower standard deviation will be more consistent.<br />

Thus, team A is more consistent than team B.<br />

Question 5:<br />

The sum and sum of squares corresponding to length x (in cm) and weight y<br />

(in gm) of 50 plant products are given below:<br />

50 50<br />

2<br />

50 50<br />

2<br />

i1 i<br />

i1 i<br />

i1 i<br />

i1<br />

i<br />

x 212, x 902.8, y 261, y 1457.6<br />

Which is more varying, the length or weight?<br />

Solution 5:<br />

50 50<br />

x 212, x 902.8<br />

i<br />

i1 i1<br />

Here, N = 50<br />

50<br />

2<br />

i<br />

yi<br />

i1 212<br />

Mean, x= 4.24<br />

N 50<br />

50<br />

2 1<br />

2<br />

Variance 1 xi-x<br />

<br />

N i1<br />

1<br />

50<br />

2<br />

xi<br />

-4.24 <br />

50 i1<br />

1<br />

50<br />

2<br />

xi<br />

8.48x<br />

i<br />

17.97<br />

50 i1<br />

<br />

<br />

1<br />

50 50<br />

2<br />

<br />

<br />

xi<br />

8.48 xi<br />

17.97 50<br />

<br />

50 <br />

<br />

i1 i1<br />

<br />

1 902.8 8.48 212 898.5<br />

50<br />

<br />

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