Answer to Question #173582 in Statistics and Probability for ANJU JAYACHANDRAN

Question

1. a) Following is the distribution of marks (out of 25) obtained by 10 students in Physics

and Mathematics.

No. Physics

(X )i

Mathematics

(Y )i

2 Xi

2 Yi

XiYi

1 18 21 324 441 378

2 20 23 400 529 460

3 11 14 121 196 154

4 20 23 400 529 460

5 14 17 196 289 238

6 15 18 225 324 270

7 13 16 169 256 208

8 16 19 256 361 304

9 17 20 289 400 480

10 20 23 400 529 460

Total 164 194 2780 3854 3412

Draw a scatter diagram for all the 10 students and calculate the correlation between

marks of Physics and Mathematics.

Answer 1

a) scatterplot

b)correlation

$r = \frac{N\sum{XY}-(\sum{X}\sum{Y})}{\sqrt{ [N \sum{x^2}-(\sum{x})^2 ][N \sum{y^2}-(\sum{y})^2 }]}$ $=\frac{10*3272-(164*194)}{\sqrt{[10*2780-164^2][10*3854-194^2]}}$

=1