Density Curves
Weight of newborns

Nearest pound
4

5
6
7
8
9
Nearest tenth of pound
4
5
6
7
8
9
Fit more & more rectangles

It approaches a curve as the rectangles
become smaller & has greater accuracy.
Density Function
•
Describes the overall pattern of a distribution.
•
The area under the curve and above any interval
of values on the horizontal axis is the proportion
of all observations that fall in that interval.
•
The graph is a smooth curve called the density
curve.
•
Total area under the curve = 1.
Uniform Distribution

All occur in equal distributions
Ex:
.5 if 4  x  6
f ( x)  
0 otherwise
What’s the area from 4.5 to 5.5?
What’s the area from 5.5 to 6?
If we have a uniform continuous
function from 3 to 8, find the
height.
Ex.
0.02
50 minutes

Find P(x < 10)

Find P(x < 35)
0.25
Ex:

Find P(x<4)

Find P(x<2)
0.02
Ex:
50

Find P(x<20)

Find P(x>70)

Find P(20<x<70)
100
Homework
Page 353 (1-7) odd (21, 27, 33, 34)
 Worksheet
