Friday, January 29, 2010

Growing by Denominators

Find the smallest fraction, which will triple in size, when you add its denominator to its numerator and its denominator.

Find the smallest fraction which will quadruple when the same process is applied.

6 Comments:

Anonymous Anonymous said...

Not sure if they're the smallest?

1/5 > 6/10 =3/5

1/7 > 8/14 =4/7

but they work!

regards, Curtis

January 29, 2010 7:54 AM  
Anonymous Zaux said...

good work Curtis

January 29, 2010 8:27 AM  
Anonymous Anonymous said...

forgot the equation:

fraction x/y

3(x/y) = x+y/2y
thus 3x/y = x+y/2y
thus 6x/2y = x+y/2y
thus 6x = x+y
thus 5x = y
if x=1.....y=5
hence 1/5

n(x/y)= x+y/2y
(2n-1)x = y

so for 19 times fraction is 1/37

I think!!
regards, Curtis

January 29, 2010 8:33 AM  
Blogger Chris said...

Let n/d be the fraction.
Then require (n+d)/(d+d) = 3n/d
=> n+d = 6n => d = 5n => n/d = 1/5
and (n+d)/(d+d) = 6n/10n = 3/5 = 3*(1/5)

January 29, 2010 2:17 PM  
Blogger Chris said...

This post has been removed by the author.

January 29, 2010 2:38 PM  
Blogger Chris said...

.. sorry Curtis, I've only just realised that's what you did. If you'd written 3(x/y) = (x+y)/(2y) I wouldn't have posted.

January 29, 2010 7:24 PM  

Post a Comment

Links to this post:

Create a Link

<< Home