SOLUTION: Find the variation constant and an equation of variation in which y varies directly as x, and y = 20 when x = 40.

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Question 1098795: Find the variation constant and an equation of variation in which y varies directly as x, and y = 20 when x = 40.
Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39617) About Me  (Show Source):
Answer by greenestamps(13200) About Me  (Show Source):
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Direct variation means the "output" function value gets larger or smaller as the input value gets larger or smaller. This is represented by an equation of the form y+=+kx, where k is the variation constant.

If, as in this problem, you are given an x and a y value in a direct variation problem, you can find the variation constant k by plugging the given x and y values in the general form of the equation.
20+=+k%2840%29
0.5+=+k

The variation constant is 0.5, or 1/2.