Mice and Medians

"What size mouse would you like?" asked the lady in the pet store.

Clay thought for a moment. The little ones looked kind of delicate. The big ones looked like they'd eat too much.

"I'd like a medium-sized one," he announced. "Halfway between the biggest and the smallest!"

Can you find which one Clay wanted?

It was hard to tell, wasn't it? Clay and the pet-store guy arranged the gerbils from smallest to largest. Now find the one in the middle:

It's a lot easier when they're arranged, isn't it?

The purple mouse has three mice which are smaller, and three mice which are larger. We'd say that this mouse is the MEDIAN

The median is the element that is right in the middle of a set.
Have you heard this word used somewhere (hint: think "streets")

The median is that strip down the center of divided roads.

In statistics, the median is a number that's in the middle of a list.

What's the median of this list?

3, 5, 10, 11, 14

"10" has two numbers which are less than it, and two numbers which are greater than it, so it's the median. What is the median of this list?

11, 5, 3, 14, 10

11, 5, 3, 14, 10

Step 1: Arrange the Elements in Numerical Order

3, 5, 10, 11, 14

Step 2: Find the Middle

3, 5, 10, 11, 14

What about this set?

1, 4, 2, 3, 7, 5

What is different here?

Try Another..
1, 4, 2, 3, 5, 7

Step 1: Put them in order

1, 2, 3, 4, 5, 7

Step 2: Find the middle

1, 2, 3, 4, 5, 7

This list has two numbers in the middle!

In this case, the median is the AVERAGE, or MEAN of these middle two values.

Cick here to review what an average is. You can also go back and review the lesson on means

Averaging two numbers is pretty easy. Just find the the number in the middle. You can do this very easily if the numbers are consective, like 3 and 4, or 98 and 99. It would just be 3.5, or 98.5, or whatever.

For others, like 14 and 89, just add them together and divide by two.

(14+82)/2 =

PE03849_.WMF (8320 bytes)

What is median of this list:

65, 25, 117, 35

Find the Median:

65, 25, 117, 35

Step 1: Arrange data in order

25, 35, 65, 117

Step 2: Find the middle(s)

25, 35, 65, 117

35 and 65 are both in the middle.

Step 3: If there's more than one middle value, average these two values.

35+65 = 100, 100/2 = 50
The median is 50.

When will the list have only one middle value, and when will it have two middle values?

Well that's all finished.

You should know all about Medians by now. I guess now I 'll take my mice home!