Z - Scores
The concept
Let's Look at the Physics Test!
n We know its mean is 50.
n The Standard Deviation is calculated to be 10 (someone used their calculator).
n Remember the SD is the distance from the Mean from to the Point of Inflection (change in direction of the curve)
The 4th Big Idea!!
What's our Physics Freak Roommate's Z - score
And Why is She Happy!
1. The roommate's score is 10 points above the mean or one SD above the mean.
2. Her Z - Score Equals 1 because:
Z = (Score - Mean)/SD
Z = (60 - 50) / 10
Z = 1
3. Let's do it again! The student down the hall runs in to our gang's room. She yells - I got a 84!! Yahoo!
2. Her Z - Score Equals 3.4 because:
Z = (Score - Mean)/SD
Z = (84 - 50) / 10
This is a bright young person. Let's look at the Z-Score ruler on the Normal Curve. She gets a very big happy face
She's done better than almost 
everyone in the class!
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