How do I solve for a variable in a standard normal distribution using R?

Question

I'm trying to solve this expression using R and I have no clue.

P(Z >= c) = 0.025

I found P(Z < c) = 0.975 using the complement rule but do not know how to proceed further.

Answer 1

If you have the cumulative distribution function (CDF) , think about the inverse.

Here, p = 0.975 .

Fortunately, other people have already built functions like these. Compare the definition of the inverse CDF to the quantile function for insights into why the letter q is used by some packages.

I'll leave the rest up to you.