Normal distribution with R

Hi James
its just simple calculus, since with
q90<-qnorm(.9,me,sd)
q10<-qnorm(.1,me,sd)

mean<-(q90+q10)/2    # the normal distribution is symmetric around the mean
sd<-(q90-q10)/ (qnorm(.9)-qnorm(.1)) #  between 10th and 90th are 
qnorm(.9)-qnorm(.1)=2.563103sds

hth.

guox at ucalgary.ca schrieb:

If we knew two pth quantiles for a normal distribution,
is it possible that we can find mean and sigma for the normal distribution
using R?

Let x ~ norm(mean, sigma).
Suppose that qnorm(0.9,mean,sigma) and qnorm(0.1,mean,sigma) are known.
Can we find mean and sigma using R?

Thanks,

-james

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