The following table gives the average temperature, T, at a depth d, in a well at Belleterre, Quebec.

d, depth (m) 25, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300

T, temperature (C∘) 5.50, 5.20, 5.10, 5.10, 5.30, 5.50, 5.75, 6.00, 6.25, 6.50, 6.75 , 7,00

Evaluate ΔT/Δd at the following intervals

a) 75≤ d≤ 125 ΔT/Δd =

b) 100 ≤ d ≤ 200 ΔT/Δd =

c) 2 5≤ d ≤ 75 ΔT/Δd =