How do you find Xp without using Standard normal distribution table but only using 1sigma,2sigma,3sigma rule

Question

Does someone know how I find $Xp$ if I do not have access to standard distribution table.

With the table its easy, let's suppose we need $Xp$ of $0.990$. If we have acsess to our table we know that this is $2.326$ but what if we don't have this table at hand? We have to use $\sigma$, $2\sigma$, $3\sigma$-rule (some also call this 68-95.99.7 rule)

I know you have to draw guauss shape curve thing: https://exceluser.com/wp-content/uploads/2018/08/normalcurve.jpg

but I don't know what to do next, how do you then use this hand-drawn curve to figure out using sigmas that Xp of 0.990 is 2.326

Sorry for that wierd question, words for statistics are very different in our own language so half of how all this is called in english is a mistery to me

Thanks for Anwsering and Best Regards

Answer 1

but I don't know what to do next, how do you then use this hand-drawn curve to figure out using sigmas that Xp of 0.990 is 2.326

simply you cannot. you can only say that you quantile is $2<X_p<3$