Question

If the random variable x is normally distributed with a mean equal to .45 and a standard deviation equal to .40, then P(x ≥ .75) is:

Answer 1

z = (x-mean)/sd

Answer 2

z = (.75 - .45)/.40

Answer 3

the rest is gotten from a ztable or a calculator i believe; you got a ti83?

Answer 4

I got a ti89 :)

Answer 5

and the table too

Answer 6

press: 2nd, vars, normalCDF ( .75,9999,.45,.40 )

http://www.wolframalpha.com/input/?i=normalCDF+%28+.75%2C9999%2C.45%2C.40+%29

.2266 i believe

Answer 7

i got a ti83 :) cant afford an 89 lol

Answer 8

Thanks for the help. Currently trying to figure out how to do on calc

Answer 9

might be under home

Answer 10

http://answers.yahoo.com/question/index?qid=20070918160009AAr6Q8b

this one says under apps

Answer 11

How would we do it from just the table alone?

Answer 12

determine the "z"

z = (.75 - .45)/.40 = .7500

and depending on how your table is set up this can go a few ways

Answer 13

do you know if your z is measured from the middle (the mean) of from the left end?

Answer 14

Left end

Answer 15

Ok I think i got it. .75 on the table corresponds to .7734. 1-.7734=.2266

Answer 16

ok; the z score itself is read:

0.70 on the left side; and .05 on the top; and where they cross at is your "area" covered to the left

Answer 17

yes

Answer 18

Thanks :)

Answer 19

.05
|
|
0.70 ----- .7734


area to the left of .75: .7734


area to the right is: 1 - .7734


your welcome :)