For the same output 30, 34, 37, 41 and 48 (2020 to 2024, $x$ in years from 2022), what is the slope $b$ of the least-squares trend line?

Explanation

1. 01

   $\sum xy = -60 - 34 + 0 + 41 + 96 = 43$ and $\sum x^{2} = 10$.

2. 02

   $b = \frac{43}{10} = 4.3$ a year.