I need help with a probability & statistics question

Question

A mathematics teacher wanted to see the correlation between test scores and homework. The homework grade (x) and test grade (y) are given in the accompanying table. Write the linear regression equation that represents this set of data, rounding all coefficients to the nearest tenth. Using this equation, estimate the homework grade, to the nearest integer, for a student with a test grade of 74. 

Homework grade (x) 74,74,73,70,76,82,70

Test grade (y) 68,68,56,76,63,70,74,80

Answer 1

Note: There was a missing data point in the Homework Grade. So I put a 74 to get 8 data points on each variable.

Put these data points in Excel. In the Data Analysis tab, scroll down and click on Regression. Input Y range for Test Grade and Input X range for Homework Grade.

y = -0.4x + 98.3

When you increase your homework score by 1 point, you lose 0.4 points on your test.

-0.4x + 98.3 = 74 → -0.4x = -24.3 → x = 60.75 ≈ 61

A student will earn a 61 on his/her homework if he/she earns a 74 on an exam.