Linear Regression
Fit ŷ = a + bx by least squares and predict.
Best-fit line through the scatter
ŷ = 0.64 + 1.54·x
Predict score for
8 hours → 12.928571428571429 marks
Slope formula
b = (n·Σxy − Σx·Σy) / (n·Σx² − (Σx)²)
= (8·617 − 52·85) / (8·380 − 2704) = 1.54
Every extra hour of study adds about 1.5 marks, on average. Intercept a = 0.64.