Q. If x and y vary directly and y is 55 when x is 11 , find y when x is 4 .Answer: y=
Write Equation: Write the equation that represents the direct variation between x and y. Since y varies directly with x, the equation can be written as y=kx, where k is the constant of variation.
Find Constant: Use the given values to find the constant of variation k. We know that y=55 when x=11. Substitute these values into the direct variation equation to find k. 55=k×11
Solve for k: Solve for k.Divide both sides of the equation by 11 to isolate k.k=1155k=5
Write with k: Write the direct variation equation with the found value of k. Now that we have found k to be 5, the direct variation equation is y=5x.
Find y: Find y when x is 4 using the direct variation equation.Substitute x=4 into the equation y=5x to find y.y=5×4y=20
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