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X is directly proportional to A² and A is inversely proportional to Y. If X is 97 when Y is 6, find X when Y is 2.
Question

X is directly proportional to A² and A is inversely proportional to Y. If X is 97 when Y is 6, find X when Y is 2.

A.

873

B.

871

C.

872

D.

875

Correct option is A

Given:

X A2\propto A^2​​

A 1Y\propto \dfrac{1}{Y}

when Y = 6, X = 97; find X when Y = 2

Formula Used:

Since A 1Y \propto \dfrac{1}{Y}​, A=kY = \dfrac{k}{Y}​ 

XA2 X=KY2X \propto A^2 \implies X = \dfrac{K}{Y^2}​​

Therefore, X Y2=constant^2 = \text{constant}​​

Solution:
At Y = 6: K=XY2=97×62=97×36=3492 = X Y^2 = 97 \times 6^2 = 97 \times 36 = 3492​​
At Y = 2: X=KY2=349222=34924=873 = \dfrac{K}{Y^2} = \dfrac{3492}{2^2} = \dfrac{3492}{4} = 873​​

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