|By mathz on Monday, January 20, 2003 - 12:58 am: Edit|
the numerator and denominator of a fraction are in the ratio 2:3.
If 6 is subtracted from the numerator, the result will be a fraction that has a value 2/3 of the original fraction. What is the numerator of the original fraction??
answer: 18...but HOW!?
|By hey on Monday, January 20, 2003 - 01:13 am: Edit|
Let n be the numerator and d be the denominator.
Then n/d = 2/3 ==> d = 3n / 2
When you subtract 6 from n, you get n-6.
So (n-6)/d = (2/3) (2/3) = (4/9)
Plugging in d from the first equation, you get
(n-6) / (3n/2) = 4/9
Since (n-6) / (3n/2) = 2(n-6) / (3n),
(2n - 12) / 3n = 4/9
Bringing 3n to the right side, you get
2n - 12 = (4/9) (3n) = (4/3 n)
Putting all the n's on the left and numbers on the right, you get
2n - (4/3)n = 12
So (2/3)n = 12
So n = 18.
|By mathz on Monday, January 20, 2003 - 01:28 am: Edit|
for some random reason i can never SEE it; it seems so easy once you see the answer.
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