Help with elementary statistics?:)

Question

lukecrayonz · Answer

lukecrayonz · Answer

My savior <3

anonymous · Answer

I'm fairly certain there's more than one way to break up the data into categories, but I think the simplest one would be to label the first as all ages between (and including) 51 to 55, the second as between 56 and 60, and so on.

The frequency of each category would be the number of data points that fall within each particular interval.

So, as an example, let's say my data is the set of natural numbers from 1 to 10, or $\{1,2,3,4,5,6,7,8,9,10\}$.

I'd call my categories 1-5 and 6-10.
In 1-5, I have 5 numbers: 1,2,3,4,5.
In 6-10, I have 5 numbers as well: 6,7,8,9,10.
So for this case, $f=5$ for both categories, and $\sum f=10$.

lukecrayonz · Answer

What exactly does the sigma mean in this?

lukecrayonz · Answer

Just the AVG of all the frequencies?

anonymous · Answer

$\Sigma$ is used to denote a summation.

For example,
$$\sum_{n=1}^3 n=1+2+3$$
In this case, $n$ is called the "index," which takes on a certain set of values. This notation implies the set of natural numbers, starting at the lower index ($n=1$, below the sigma) and ending at the upper index ($n=3$, above sigma).

When you're given a summation without an index, it should be obvious what it's referring to. In regards to your problem, you're simply summing up all the frequencies $f$.