Direct variation word problem

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.
EmyJae
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Direct variation word problem

Postby EmyJae » Fri Oct 07, 2011 2:48 am

kepler's third law of planetary motion states that the square of the period of revolution T of a planet varies directly with the cube of its mean distance a from the sun. if the mean distance of earths from the sun is 93 million miles, what is the mean distance of the planet mercury from the sun, given that mercury has a "year" of 88 days. How do you solve for how far mercury is from the sun

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maggiemagnet
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Re: Direct variation word problem

Postby maggiemagnet » Fri Oct 07, 2011 6:26 pm

EmyJae wrote:kepler's third law of planetary motion states that the square of the period of revolution T of a planet varies directly with the cube of its mean distance a from the sun. if the mean distance of earths from the sun is 93 million miles, what is the mean distance of the planet mercury from the sun, given that mercury has a "year" of 88 days. How do you solve for how far mercury is from the sun

You solve by setting up the variation equation that they've described to you, and then plugging in number they've given you, so you can solve for the number they've asked you for. You can learn how to set up the variation equation here. Then use the numbers for Earth (the distance and the year length in days) to find the variation constant. Then set up the same equation with that constant and the number they give you for Mercury and solve.
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