Calculate the probability that the electron in the ground state of a hydrogen atom is in the region 0 < r < 3.75a0.
The Attempt at a Solution
I am confused because I am not sure if I am supposed to use 3.75a0 as my radius. I guess I am not supposed to since I did that and got it wrong. I cannot figure out what else to do. However, I have also seen the probability density written as:
If this is the correct formula, I am not sure what to use for delta r.
Any help would be much appreciated.