Question

Help please :)
Find the number z such that the proportion of observations that are less than z in a standard Normal distribution is 0.9

I know I'm supposed to look at the standard normal deviation table, but when I tried this before, I couldn't find the number =/ Am I supposed to do something?

Answer 1

@jim_thompson5910 can you help??

Answer 2

what you want to find is the value of k such that

P(Z < k) = 0.9

Answer 3

so if you can't use a calculator, you can use either the standard normal distribution CDF table or the inverse standard normal distribution CDF table

Answer 4

does that help?

Answer 5

if I were to use the calculator, is the formula above already in the system and I just plug in my number, or would I have to know what p or z already are and solve for k like that?

Answer 6

depends on the calculator, what kind do you have?

Answer 7

scientific but i have a TI 83 somewhere

Answer 8

ok it would be better to use a TI83

however, you can use wolfram alpha if you want?

Answer 9

i tried it, it explained what i already have in my notes so guess I'll just keep rereading it, thanks tho :)

Answer 10

alright let me know if you need any more help with it