Question

3. Given the data in problem 2, if a student received a score of 80 on the midtest, what would be the best prediction for the grade on the lasttest? Please compute a line of best fit and predict what the final grade should be.

Question 2 data :

Midtest 85      90     72     75     82     95     80      83     81     95

Last test 83      91    75     85     65     92      83      86    79     98

Answer 1

using excel>data>data analysisi>regresison

'we have

SUMMARY OUTPUT
Regression Statistics
Multiple R	0.675532
R Square	0.456343
Adjusted R Square	0.388386
Standard Error	7.290355
Observations	10
ANOVA
	df	SS	MS	F	Significance F
Regression	1	356.9058	356.9058	6.71516	0.032045
Residual	8	425.1942	53.14927
Total	9	782.1
	Coefficients	Standard Error	t Stat	P-value	Lower 95%	Upper 95%
Intercept	15.16492	26.5478	0.571231	0.58353	-46.0544	76.38425
mid	0.817841	0.315603	2.591363	0.032045	0.09006	1.545622

we have the equation

last = 15.165 +0.818 *mid

for mid = 80

last =15.165 +0.818 *80 = 80.61