What did galton use to calculate how strong the relationship was for the line of best fit?

10¹⁸ ergs

Step-by-step explanation:

From the question,

Using the expression

M = log(E/10¹³)................. Equation 1

Where M = Richter magnitude of earth quake, E = Energy released in ergs.

Given: M = 4.0

Substitute into equation 1 amd solve for E

4 = log(E/10¹³)

Log(E/10¹³) = (4×5)/4

Log(E/10¹³) = 5

E/10¹³ = 10⁵

E = 10⁵×10¹³

E = 10⁵⁺¹³

E = 10¹⁸ ergs