Z-scores

Z-score formula:
Z= (x-xbar)
---------
ox
" the z score measures the distance plus or minus from the mean in units of std deviation"
x- what you got
xbar- what they got
ox- std deviation
if number is negative its BAD, positive, GOOD!
TO CLR LIST 2nd + 4 ENTER

Characteristics of normal distribution:

Characteristics of normal distribution:
Theoretical (aproximation)
Symmetry about mean
Follows this rule:
68-95-99.7
mean-median-mode
2nd vars gets you to Normal cdf (low value, high value, x, ox)
How do you find out how many fish longer than 40 cm?
Normal cdf(40, E99)
E=2nd --> ,

Boundaries, grouped data

Once you have your grouped data, enter it into your calculator in your lists and then
STAT--> CALC--> 1-var stats--> L2, L2

Mean Median and Mode.
Mean - avg
Median - middle number
mode - happens most
To get std deviation - stat -> calc -> 1-var stats
x-mean
Ex-sum of all numbers
Ex2- sum of all numbers squared
sx- DONT USE
ax- USE! std. dev.
std dev, no spread - 0
big spread, high