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Bunuel
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I have a question here, why is it wrong that I elevated the whole expression to the thrid (x-(1-a/100))^3?
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Any suggestions on ways to do this by plugging in?
­You could just choose values for x and a but because of the complexity of the formula for volume here, I don't think it would make it much easier
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­A possible solution:

­
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Feel like I missed something, is there any reason why I can't simplify the cube root of 1-a/100 to 1 - cuberoot(a/100), therefore making E the answer?
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Feel like I missed something, is there any reason why I can't simplify the cube root of 1-a/100 to 1 - cuberoot(a/100), therefore making E the answer?
In general, \(\sqrt[3]{1 - \frac{a}{100}}\) is not equal to \(1 - \sqrt[3]{\frac{a}{100}}\).
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Bunuel - given geometry is not there, can this question come in exam ?
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Bunuel - given geometry is not there, can this question come in exam ?

This is GMAT Prep Question:



It does not test any specific geometry knowledge, and the formula is provided, so questions like this can still appear on the exam.
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4/3pix^3[(100-a)/100] = 4/3pi*y^3
y value is what we need.

Cancelling 4/3pi:
x^3[(100-a)/100] = y^3
Taking cube root:

y = x*[(100-a)/100]^1/3

Answer: Option D
Bunuel
A spherical balloon originally had a radius of x centimeters. The balloon was partially deflated by letting out some air so that the volume of the balloon decreased by a%. If the balloon remained spherical while the air was being let out, which of the following expressions in x and a gives the radius, in centimeters, of the partially deflated balloon?

(Note: The volume of a sphere with radius r is \(\frac{4}{3}πr^3\).)

A. \(x(100 - a)^3\)

B. \(x(1 - \frac{a}{100})^3\)

C. \(x(\sqrt[3]{100 - a})\)

D. \(x(\sqrt[3]{1 - \frac{a}{100}})\)

E. \(x(1 - \sqrt[3]{\frac{a}{100}})\)
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