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Question: A teacher wishes to know whether there is any relationship between the hours of study and the test scores of the students. Ten students were selected randomly and were given a test. Test the hypothesis that there is a significant relationship between hours of study and test scores at α = 0.01 using the P-value method and determine the equation of the regression line and predict the value for y′ when x = 16.
Hours of study (x)6118111214157126
Test scores (y)50756570788590658055


A ) yes, y′ = 32.53 + 3.8x, 98.33
B ) no, y′ = 32.53 + 3.8x, 98.33
C ) yes, y′ = 32.53 + 3.8x, 93.33
D ) no, y′ = 32.53 + 3.8x, 93.33

Steps to derive

1 Make a table with values for x, y, x2, y2, xy


2 r = n(Σxy)-(Σx)(Σy)[n(Σx2)-(Σx)2][n(Σy2)-(Σy)2]

3 r = + 0.969
 [Substitute the values and simplify.]

4 Therefore, r is significant and the regression line can be found for any predictions.

5 State the hypothesis: H0: ρ = 0 and H1: ρ ≠ 0

6 Compute the test value, t = r n-21-r2 = 11.09
 [Substitute the values and simplify.]

7 We can see that the t - value (11.09) obtained and with degrees of freedom = 8 lies beyond 3.355

8 Hence, P - value falls beyond 0.01, i.e., P - value < 0.01, reject the null hypothesis, since P - value < 0.01

9 Therefore, there is a significant relationship between the hours of study and the test scores.

10 Regression line equation is y′ = a + bx
a = (Σy)(Σx2)-(Σx)(Σxy)n(Σx2)-(Σx)2
b = n(Σxy)-(Σx)(Σy)n(Σx2)-(Σx)2

11 a = 32.53, b = 3.8
 [Substitute the values and simplify.]

12 Therefore, the equation of the regression line y′ = a + bx is y′ = 32.53 + 3.8x

13 When x = 16, y′ = 93.33



Hence the right answer is Option C

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