probability

[rgentil32]

A sample of people's heights has mean of 5.6 and a standard deviation of .0155. Find c such that between 5.6 − ? and 5.6 + ? is included 98% of the heights.

My work:
I found a z score of .9599 for X < 5.6. How do I start to find the "c" values above?

 

[Dr.Peterson]

That can't be right! The z-score for the mean is by definition 0! (And if you mean that the probability is .9599, that has to be 0.5.)

Please show us how you got that number. (I have a guess, but I need to see what you are thinking.)

 

[rgentil32]

Dr Peterson,
Here is a picture of my work

 

[Steven G]

Dr Peterson,
Here is a picture of my work

OK, fine. Now based on YOUR z-table can you please explain what that .9599 means. I will help you a bit. 0.9599 is an area, can you please tell us what area it represents. Look at the the picture above your z-table.

 

[Dr.Peterson]

Dr Peterson,
Here is a picture of my work

Where did 5.6271 come from? That isn't in the problem as you quoted it.

In any case, you need to find the z-score not for that number, but such that that interval above and below the mean will contain 98% of the values. So you'll be reading your table backwards, not forwards as you are doing it.

(Unless I am totally missing what you did, and somehow 5.6271 is relevant.)