#### Correlation and Regression Analysis Three Marks Questions

11th Standard

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Time : 00:45:00 Hrs
Total Marks : 30
10 x 3 = 30
1. Calculate the correlation co-efficient for the following data.

 X 5 10 5 11 12 4 3 2 7 1 Y 1 6 2 8 5 1 4 6 5 2
2. Calculate the coefficient of correlation between X and Y series from the following data.

 X Y Number of pairs of observation 15 15 Arithmetic mean 25 18 Standard deviation 3.01 3.03 Sum of squares of deviation from the arithmetic mean 136 138

Summation of product deviations of X and Y series from their respective arithmetic means is 122.

3. A random sample of recent repair jobs was selected and estimated cost and actual cost were recorded.

 Estimated cost 300 450 800 250 500 975 475 400 Actual cost 273 486 734 297 631 872 396 457

Calculate the value of spearman’s correlation coefficient.

4. The rank of 10 students of same batch in two subjects A and B are given below. Calculate the rank correlation coefficient.

 Rank of A 1 2 3 4 5 6 7 8 9 10 Rank of B 6 7 5 10 3 9 4 1 8 2
5. The following table shows the sales and advertisement expenditure of a form

Coefficient of correlation r= 0.9. Estimate the likely sales for a proposed advertisement expenditure of Rs. 10 crores.

6. Calculate the coefficient of correlation from the following data:
ΣX=50, ΣY=–30, ΣX2 =290, ΣY2 =300, ΣXY=–115, N=10

7. Calculate the correlation coefficient from the data given below:

 X 1 2 3 4 5 6 7 8 9 Y 9 8 10 12 11 13 14 16 15
8. Calculate the correlation coefficient from the following data:
ΣX=125, ΣY=100, ΣX2 =650, ΣY2 =436, ΣXY=520, N=25

9. A random sample of recent repair jobs was selected and estimated cost, actual cost were recorded.

 Estimated cost 30 45 80 25 50 97 47 40 Actual cost 27 48 73 29 63 87 39 45

Calculate the value of spearman’s correlation.

10. The following data pertains to the marks in subjects A and B in a certain examination. Mean marks in A = 39.5, Mean marks in B= 47.5 standard deviation of marks in A =10.8 and Standard deviation of marks in B= 16.8. coefficient of correlation between marks in A and marks in B is 0.42. Give the estimate of marks in B for candidate who secured 52 marks in A.