Hi Tove, I thought I should highlight this as you seem to have missed it?
We have no context for why you calculate b1, and why you chose 0.02 in particular.
consider
plot(pnorm(q = 0:100,100,15))

I wonder if perhaps 0.02 was assuming 2% quantile, whereas that would be 2, as q would be in the range 0 to 100 rathen than 0 to 1 ( I think ?)