Expert Solution - Excel IF Problems

Question description:
This user has given permission to use the problem statement for this blog.

There is a 62â??% chance that X is above whatâ?? value? if n =25 mean = 100 STD =25

Solved by T. J. in 40 mins

This is the chat thread from the real Excelchat help session. It contains no private user information.

Excelchat Expert 11/09/2018 - 12:02

Welcome to Got it Pro

Excelchat Expert 11/09/2018 - 12:03

Please tell a bit more about the requirement so that i can help better

User 11/09/2018 - 12:03

Hi Dianne.

User 11/09/2018 - 12:03

I need to find bar X

Excelchat Expert 11/09/2018 - 12:04

Do you have the graph for normal distribution?

User 11/09/2018 - 12:05

no I do not know how to use it, can you step by step help me set it up on excel

Excelchat Expert 11/09/2018 - 12:08

Do you know this formula Z = (x-mean)/StdDev

User 11/09/2018 - 12:10

yes, but when I uses it on this part of the problem it do not work

Excelchat Expert 11/09/2018 - 12:13

Do you have z table with you?

User 11/09/2018 - 12:14

I do

Excelchat Expert 11/09/2018 - 12:14

so what is the z value when probability is 62%?

Excelchat Expert 11/09/2018 - 12:15

i think it would be nearly 0.4

Excelchat Expert 11/09/2018 - 12:15

what do you see?

User 11/09/2018 - 12:16

I dont know how to read it on the positive or negative side

Excelchat Expert 11/09/2018 - 12:16

there is value for Z and then there is column which says 00

Excelchat Expert 11/09/2018 - 12:16

value in column 00 should be nearly 65%

Excelchat Expert 11/09/2018 - 12:17

and see z value against it

User 11/09/2018 - 12:18

0.31

Excelchat Expert 11/09/2018 - 12:22

-0.31 = (xbar - 100)/(25/sqrt(25))

Excelchat Expert 11/09/2018 - 12:22

Do you see this formula now?

Excelchat Expert 11/09/2018 - 12:22

Just get x bar from this

Excelchat Expert 11/09/2018 - 12:23

once you get the z value just equate it to this formula

Excelchat Expert 11/09/2018 - 12:23

Let me know if you understand

Excelchat Expert 11/09/2018 - 12:23

98.45% probability

Excelchat Expert 11/09/2018 - 12:24

See on spreadsheet on right

Excelchat Expert 11/09/2018 - 12:24

Let me know if that helps you out

User 11/09/2018 - 12:25

what I do not get is the reading of the chart, why not use 38 since 100-62 = 38

User 11/09/2018 - 12:26

where did the xbar come from - 100 that the number I need to know how to get

Excelchat Expert 11/09/2018 - 12:26

100 is mean

Excelchat Expert 11/09/2018 - 12:26

that is a formula

Excelchat Expert 11/09/2018 - 12:27

Z value = (xbar - mean)/(STD/sqrt(n))

Excelchat Expert 11/09/2018 - 12:27

This is the formula for normal distribution

User 11/09/2018 - 12:28

the xbar what number do you use to get that. I put in and it didnot come out to 98.45

Excelchat Expert 11/09/2018 - 12:28

so if mean is 100 there is 62% probability that X is above 98.45

Excelchat Expert 11/09/2018 - 12:28

I have found out x bar

Excelchat Expert 11/09/2018 - 12:29

-0.31 = (xbar - 100)/(25/sqrt(25))

Excelchat Expert 11/09/2018 - 12:29

This is the equation

Excelchat Expert 11/09/2018 - 12:29

-0.31= (xbar - 100)/(25/5)

Excelchat Expert 11/09/2018 - 12:29

-0.31= (xbar - 100)/(5)

Excelchat Expert 11/09/2018 - 12:30

-0.31*5= (xbar - 100)

Excelchat Expert 11/09/2018 - 12:30

X bar = 100-0.31*5

Excelchat Expert 11/09/2018 - 12:30

Do you get it now?

Excelchat Expert 11/09/2018 - 12:31

Please let me know if this helps you out?

Excelchat Expert 11/09/2018 - 12:31

Are you there?

Excelchat Expert 11/09/2018 - 12:31

Looking forward to good ratings and reviews from you

User 11/09/2018 - 12:31

I'm trying to work it now to see

Excelchat Expert 11/09/2018 - 12:31

Sure please try

User 11/09/2018 - 12:32

It help thank you