If y varies directly with the square of x and y = 4.3 when x = 5, what is the value of y when x = 6?

A) 0.2
B) 3.0
C) 5.2
D) 6.2
E) 209.3

Direct variation (aka direct proportionality) means that the ratio of the two variables will always be the same. In this case, \dfrac{y_1}{{x^2}_1}=\dfrac{y_2}{{x^2}_2}.

Once you have that set up, you can solve fairly simply by plugging in the values you’re given:


Round it and you land on D. 


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