Function of qnorm() in R

Question

I have read the documentation on qnorm() but could not really understand what it does. Can you please answer in detail what qnorm() does?

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Answer 1

The function qnorm() aims to find the boundary value, A in P(X < A), given the probability P.

For example, suppose you want to find the 85th percentile of a normal distribution whose mean is 70 and whose standard deviation is 3. Then you ask for:

qnorm(0.85,mean=70,sd=3)
[1] 73.1093

From https://cran.r-project.org/web/packages/tigerstats/vignettes/qnorm.html