ssiva wrote:
Hi ,
X and Y are positive number and X is inversely proportional to Y. By what percent would the value of Y decrease , if the value of X is increases by 50%.
i followed as follows ,
since, xy = k and x increases by 50%,
y dereases by 50%
But, the answer is 33.33%.
what am i missing?
thank you
siva
Hi ssiva,
As you have rightly pointed out...
\(XY=k\) where k is a constant.
Now let X be increased by 0.5 or 50% and y be reduced by g%..
\((X+0.5X)(Y - \frac{g}{100}Y)=k\).
\(1.5X*Y(1 - \frac{g}{100})=k\).
Substituting values of k as XY from the first equation
\(1.5(1-\frac{g}{100})=1\)
or \((1-\frac{g}{100})=\frac{2}{3}\)
or \(1-\frac{g}{100}=\frac{2}{3}\)
or \(\frac{g}{100}=1-\frac{2}{3}\)
or \(\frac{g}{100}=\frac{1}{3}\)
Hence g= 33.3333.
thanks for writing.
your explanation was good. but, in case, x and y are directly proportion(x/y = K). i should replace - for + in
(Y - g/100*Y). shouldn't i?