SOLUTION: How far from the fulcrum of a teeterboard must an 80-pound boy sit to balance a 50-pound boy who is 4 feet from the fulcrum?

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Question 597437: How far from the fulcrum of a teeterboard must an 80-pound boy sit to balance a 50-pound boy who is 4 feet from the fulcrum?
Answer by math-vortex(472) About Me  (Show Source):
You can put this solution on YOUR website!
Hi, there--
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To solve this problem, we use the lever principle. A lever can be set up with unequal weights placed at different distances from the fulcrum (balancing point.) Here the lever is a teeterboard.
[I] Define the variables
w%5B1%5D is the weight of the larger boy = 80 lbs.
d%5B1%5D is the larger boy's distance from the fulcrum.
w%5B2%5D is the weight of the smaller boy = 50 lbs.
d%5B2%5D is the smaller boy's distance from the fulcrum = 4 ft.
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In order for the teeterboard to be balanced, the following equation must be satisfied.
w%5B1%5D%2Ad%5B1%5D=w%5B2%5D%2Ad%5B2%5D
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Substitute the values you know into the equation and solve for w%5B1%5D
%2880%29%2Ad%5B1%5D=%2850%29%2A%284%29
%2880%29%2Ad%5B1%5D=200
d%5B1%5D=200%2F80
d%5B1%5D=2.5
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In order to balance the teeterboard, the larger boy must sit 2.5 feet from the fulcrum.
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That's it. Feel free to email me via gmail if the explanation is unclear.
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Ms.Figgy
math.in.the.vortex@gmail.com