Blue Book Math Question Help (Pg 840, # 7)

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1

<p>Having trouble figuring out how to solve this one. I'd appreciate it if anyone could explain how they solved it. I looked at the solution on the College Board Official SAT Online course, but it was absolutely no help.</p>

<p>7) If y is inversely proportional to x and y = 15 when x = 5, what is the value of y when x = 25?</p>

<p>(a) 1/5
(b) 1/3
(c) 3
(d) 5
(e) 75</p>

2

<p>y=k/x ==> 15=k/5 ==> k=75
y=k/x ==> y=75/25 => y=3</p>

<p>Answer C) 3</p>

3

<p>5/15 = 25/y</p>

<p>Since you multiplied 5 to get from 5 to 25, inverse proportion would make you divide by 5.</p>

<p>15/5 = 3</p>

4

<p>Another way... in inverse relationship xy = k
so (5)(15) = k... k =75</p>

<p>(25)(y) = 75
y = 3</p>