"He charges 1 euro cent for the first meter, but then the price is to be increased by 50% from meter to meter."
Let's take this into account as an GP such that
GP = 1, 1.5, 2.25,... and so on
⇒ a = 1 and r = 1.5
Length of the well is 37 m i.e. the no. of terms in the GP is 37.
Now, in order to calculate the total amount, we find the sum of 37 terms in the GP
∵ \({S}_{n}={a(r^n-1)\over r-1}\)
⇒ \({S}_{37} = {1((1.5)^{37}-1)\over 1.5-1} ≈ 6552491.2\)
Thus he has to pay 6,552,491.2 euro cents.