Math CentralQuandaries & Queries


Question from Brandi, a parent:

My child came home with a worksheet regarding stem and leaf plot. I figured out how to work it with whole number but not with decimals. Can you tell me how to do this with stem and leaf graph? They are even asking for a conclusion on the information. This makes no sense to me. Please explain and send an example problem also.

Thank you!

Hi Brandi,

I found some data on 49 earthquakes that causes significant damage in California. (This comes from a textbook without a reference so it may not be real data.) The numbers are the Richter Scale measurements of the quakes and range from 5.3 to 8.3. I decided to split the data into groups 5.0 to 5.4, 5.5 to 5.9, 6.0 to 6.4 and so on and present it in a stem and leaf plot. Here is my plot

stem leaf
_______ _______________________
5. 33
5. 55788999999
6. 001111222233344
6. 55666889
7. 0000011
7. 57
8. 033

As for a conclusion, that might depend on what you child's class is discussing. I see that range with the most earthquakes is from 6.0 to 6.4 on the Richer Scale. You might also notice that only five of the earthquakes measured over 7.4. You might also express his as a percentage, 5/49 × 100 = 10.2% of the earthquakes measured over 7.4.

There is another example on the Statistics Canada site.

I hope this helps,

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