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Homework assignment |
Please complete the
following homework assignment from the textbook and deliver to me (via e-mail,
us mail, fax or by hand) by Feb. 11, 2000. Note: You should attempt all the
problems BUT ONLY TURN IN THE PROBLEMS INDICATED IN RED TO ME. Show your
work when appropriate- lists of answers will not be graded.
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HW #3: |
p. 130: 1-4,6,7,9,13,14,17,19,21,24,30,33 p. 139: 2,4,5,9-12,17-24,25 p. 151: 2-7,9,16-19,21,22,25-30 p. 169: 1,7,11,17-21,24-26,30,34,35,38 |
Writing Assignment #3
How do biologists know how
many fish are in a lake (such as Yellowstone Lake). Obviously they can't catch
all the fish in the lake or drain the lake and count them! If a biologist wants
to estimate the population of some species they often use what is know as the
capture-recapture method. In order to estimate a population of animals -
wildlife biologists often use a method called capture-recapture. For example in
order to determine the number of fish in a large lake, biologists may capture a
set number (say 50 fish), tag the fish and set them free. A week later they
will go back to the lake and capture the fish again. This time they may capture
another sample (say of 100 fish) and note how many are tagged (let's say they
find 20!) . From this they assume that 20% of the fish population of the lake
is tagged (do you see why?). So if 50 fish were tagged originally then this
would mean 50/0.20 = 250 fish are estimated to be in the lake. Your job in this
problem is to simulate this capture-recapture method using M&M candies. You
can work together on the data gathering part of this problem or have your
family or friends help you.
DATA GATHERING:
1.
Purchase
a large bag of M&M candies (there should be more than 100 items in the
bag). If this is something you do not want or can not do, ask me and I'll get
one for you
2.
Open
the bag and count the total number of M&M's (color of M&M not
relevant). This represents that total number of fish in the lake
3.
Now
place the contents of the bag in a bowl or bag and mix them up!
4.
Select
a sample of 50 M&M's from the bowl (or bag) and mark each of these with a
magic marker or using some other method(like eating a corner!), Place them back
in the bowl after they are all marked
5.
Mix
the M&M's up again
6.
Select
a sample of 100 M&M and count the number marked. Use this value to estimate
total number of M&M's in the bowl like in the example above.
Write up for me a paragraph
describing your experiment. You should include the actual number of M&M's
in the bowl, and your estimate from your sample. Make sure your compare these
values. Comment on how effective you feel this technique is for estimating
population sizes.