# Thread: Finding Mean and Standard Deviation with distribution scores

1. ## Finding Mean and Standard Deviation with distribution scores

Hello, I really have no idea how to do this question. It sounds so simple but I dont know where to start:

In a distribution of scores, X=62 corresponds to z=+0.50, and X=52 corresponds to z= -2.00. Find the mean and standard deviation for the distribution.

Thank you!

2. Originally Posted by A_mber
Hello, I really have no idea how to do this question. It sounds so simple but I dont know where to start:

In a distribution of scores, X=62 corresponds to z=+0.50, and X=52 corresponds to z= -2.00. Find the mean and standard deviation for the distribution.

Thank you!

What you need to do is treat this question as a system of two equations with two unknowns (Mu=Mean; Std=Standard deviation).

Like this:

z1 = (X1 - Mu) / Std

z2 = (X2 - Mu) / Std

where z1=0.5; X1=62; z2=-2.0; X2=52.

3. Ok that makes sense but how do I solve for two unknowns?

4. Originally Posted by A_mber
Ok that makes sense but how do I solve for two unknowns?
Do a quick Google search "solve two linear equations" and I'm sure you'll find many many cites like this one:

http://www.webmath.com/solver2.html

5. Just plug in numbers, cause u know you cant go over 62 with .5
say if you plug in 2, then 52+2=54 which is -1, 56=0, 58=+1, 60=+2,62=+3,too far. 2 is too small.
With 3- 52=-2, 55=-1 58=0 61=+1 too far 3 wnt wrk (.5 would be 59.5 )
with 4- 52=-2, 56=-1 60=0 64=+1. now sub 2 to get to .5 (62=.5)
Standard deviation answer is 4. 60 is mean(0)

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