What is a number c, such that P(z>c) = .10?

Question

Ok, so Im working on a "reverse" z-score thign for statistics and just want to know if I have the corrct answer here. Is it -.85?

Answer 1

P(z>c) = 1-P(z<=c)

P(z>c) = .10

then, 0.10= 1-P(z<=c)
P(z<=c)=1-0.10
P(z<=c)=0.9
then using the normal distribution table...
c=1.285

Answer 2

Z scores refer to the standard normal which has mean 0 and sd 1.


so, if c = 0, then P(Z>c) = P(Z
If you want P(Z>c) = 0.10 then you're looking at the right tail, so your critical Z value, or c, must be positive.

Brb, I'll go look it up...

c = 1.28

So, P(z<1.28) = 0.90 and
P(z>1.28) = 1-P(z<1.28) = 0.10