Decreasing b when a increases by 10%

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SUMMARY

The discussion centers on the relationship between two variables, a and b, where their product ab remains constant. When variable a increases by 10%, variable b decreases by 9.09%. This calculation is derived from the equation ab = constant, leading to the conclusion that the percentage change in b is not simply 10% but rather 9.09%. The assertion that a 10% increase in a results in a 10% decrease in b is incorrect.

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Homework Statement



a and B are two variables such that their
product ab = constant .If a increases by 10%,
by how much does b decrease ?

Homework Equations

The Attempt at a Solution


[/B]
ab = constant

If a changes to 11a/10 , then b has to change
to 10b/11.

% Change in b is = (b - 10b/11)/b = 9.09%

b decreases by 9.09% .

But the answer given is 10% .

Is 9.09% decrease in b correct ?
 
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Hi Jahnavi,

Yep, 9.09% decrease in b is correct.
 
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Yes.

By the same reasoning used to obtain the quoted answer you would get a 100% decrease in b if you increased a by 100%, which is ridiculous.
 
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