Question

Suppose x is a normally distributed random variable with mean = 30 and standard deviation = 8. Find the value of the random variable, call it x(0), such that

a. P(x>=x(0) = .5
b. P(x < x(0) = .025

Answer 1

and what do you have to work with?

Answer 2

and every stats student should know what the random variable for half of a normal distribution is ...

Answer 3

What do you mean by that? I believe that is all that is provided in the problem

Answer 4

i am not taking your course, so I do not know what you have at your disposal to work with .... the information is beside the point.

Answer 5

ti83, or tables, or what?

Answer 6

Oh, I see. The problem and my teacher doesn't specify. I'm not sure what method to use, but I guess by regular and calclulator methods work

Answer 7

do you have a stats calculator?

Answer 8

Yea a ti-84

Answer 9

How would I show my work though?

Answer 10

can you find the distribution menu?

Answer 11

Yea I think so

Answer 12

well, you show your work by writing down the process you took to get the answer.

i used this function and inputed this information, and got these results ...

Answer 13

you want what is called: INVNORM

Answer 14

ok i see invnorm

Answer 15

we will also prolly want to use the z formula, becuase all the invnorm function does is give us a zscore

\[z=\frac{x-mean}{sd}\]
since we are looking for x, we algebra it into
\[x=mean+z(sd)\]
given that z is the result of the invnorm function

Answer 16

a. P(x>=x(0)) = .5
invnorm(.5), hit enter


b. P(x < x(0) = .025
invnorm(.025), hit enter

Answer 17

Ok I see, thank you

Answer 18

seeing that they give you the mean and sd

x = 30 + 8z