From Walking Ray to to Basic Arithmetic Bit (BAB)

from walking Ray...

Ray the dog was getting a walk and about halfway down the block we encountered pieces of Styrofoam litter on both sides of the street. More Styrofoam litter was encountered when Ray and I turned the corner toward the park. We returned home and went on an unscheduled litter patrol. Luckily, there are was no wind; otherwise, the Styrofoam would have distributed itself around the neighborhood.


The Stryofoam litter was found on three separate streets and it was found on both sides of each street. The litter patrol took about thirty minutes and we picked-up a quarter bag of Styrofoam litter.

Sometimes likes to play with the litter it picks up. Here is the Styrofoam litter on a towel and a Styrofoam Foo banner.

to Basic Arithmetic Bit (BAB)

We wanted to know how many pieces of litter were bagged, but we weren't in the mood to do a count. Given the Styrofoam pieces were uniform sized, we estimated the count by moving the Stryofoam--a handful at a time-- from one bag to another.

We first discovered that a handful of Styrofoam litter approximates 16 pieces

We moved the Styrofoam from bag one to bag two using equally sized handfuls counting the number of transfers executed. The last handful was not full so we counted that there were 9 pieces leftover.

We estimated the number of Styrofoam pieces using the following arthimetic expression.

   pieces per handful  x  handful count  +  last handful count
    16 pieces per handful
    17 handfuls
     9 last handful

   estimated count:  16 x 17 + 9 = 272 + 9 = 281 pieces

In order to evaluate our estimate, we went ahead and physically counted that there were 293 Styrofoam pieces.

The actual count of 293 is 4.3% higher than the estimated count of 281.

The estimated count of 281 is 4.1% lower than the actual count of 293.

Is our estimate any good? Depends on how you define "good." In some cases, estimating within plus-or-minus 5% is good; whereas in other cases, it is totally unacceptable.

{ Microlitter--Styrofoam Pieces to Cigarette Butts}

Author: Gerald D. Thurman []
Created: 23 May 2005