• December 18th 2007, 10:49 AM
samantha_malone
hi, i have a chart, at 0.25, the value is 1/64
at 0.5, the value is 1/16
at 0.75 the value is 9/64
at 1, the value is 1

how can this information be written in summation notation?
• December 18th 2007, 11:01 AM
xifentoozlerix
Quote:

Originally Posted by samantha_malone
hi, i have a chart, at 0.25, the value is 1/64
at 0.5, the value is 1/16
at 0.75 the value is 9/64
at 1, the value is 1

how can this information be written in summation notation?

1/4 => 1^2/4^3
2/4 => 2^2/4^3
3/4 => 3^2/4^3
4/4 => 4^2/4^3

so i guess sum(i=1,4)(i^2/64), except that i fail to see where any sums are taken? it is just a series...
• December 18th 2007, 11:02 AM
samantha_malone
well what if i gave the following information instead:

0.2 = 0.008
0.6 = 0.144
0.8 = 0.128
1 = 1

how would i write that in summation notation?
• December 18th 2007, 11:13 AM
xifentoozlerix
are these functions? or measurements of some kind? i dont think i can help you without more context.
• December 18th 2007, 11:15 AM
samantha_malone
Quote:

Originally Posted by xifentoozlerix
are these functions? or measurements of some kind? i dont think i can help you without more context.

well basically, i was to pick points on a graph and then check their heights at that point and then find the area of a rectangle formed with the width and the height. these values represent the x values and then the area, and my assignment is to rewrite that info in summation notation.
• December 18th 2007, 11:28 AM
xifentoozlerix
I have no clue how to go about that problem. Are the areas being summed? If so, I get the impression that you are approximating the area under a curve using rectangles (presumably to eventually derive the integral from a Reimann sum). I think that is way off base though. Sorry.
• December 18th 2007, 08:35 PM
Summation notation is not exceedingly useful if you do not have an equation for the curve. You could however refer to your heights as $y_1$, $y_2$ etc, in which case you could make use of summation notation for the sum of the areas as follows (using your first set of data).
$\sum_{i=1}^{4}\frac {1}{4} y_i$