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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Mathematical Methods CAS => Topic started by: cindyy on February 28, 2010, 04:35:26 pm

Title: worded question :@
Post by: cindyy on February 28, 2010, 04:35:26 pm: A boy is three years younger than his sister. If his age three years ago was two-thirds her age at that time, what are their present ages?
Title: Re: worded question :@
Post by: TrueTears on February 28, 2010, 04:37:31 pm: x be boy age present

y be sister age present

x = y-3 ...[1]

(x-3) = (2/3)(y-3) ..[2]
Title: Re: worded question :@
Post by: cindyy on February 28, 2010, 04:45:04 pm: i just got it -__-
thanks :)
Title: Re: worded question :@
Post by: mandy on February 28, 2010, 04:45:50 pm: Do you have the answer to this? Is the sister 12 and the brother 9 ? :S
Title: Re: worded question :@
Post by: cindyy on February 28, 2010, 04:48:15 pm: thats what i got as well, so if 2 people have that answer, it must be right ;)
Title: Re: worded question :@
Post by: the.watchman on February 28, 2010, 04:49:18 pm: Quote from: mandy on February 28, 2010, 04:45:50 pm
Do you have the answer to this? Is the sister 12 and the brother 9 ? :S

Yep, that seems right! :)
Make it three
Title: Re: worded question :@
Post by: TrueTears on February 28, 2010, 04:53:38 pm: yea i think i got dat too
Title: Re: worded question :@
Post by: cindyy on February 28, 2010, 04:58:51 pm: well while we are here, i will ask another question:)

x and x+1 are two consecutive natural numbers. 1/4 of the larger exceeds 1/6 of the smaller by 1. Find the value of x.
Title: Re: worded question :@
Post by: TrueTears on February 28, 2010, 05:00:41 pm: 1/4(x+1)-1=(1/6)x
Title: Re: worded question :@
Post by: the.watchman on February 28, 2010, 05:01:27 pm: Well set up the equation first and it becomes easier:

$\frac{1}{4}(x+1) = \frac{1}{6}x + 1$

$\frac{x}{12} = \frac{9}{12}$

$x = 9$

So the two numbers are 9, 10

EDIT: beaten... :P
Title: Re: worded question :@
Post by: cindyy on February 28, 2010, 05:02:24 pm: oh what ... i totally did that i got 9/5 :S
i think i suck at this subject! Lol thank youu
Title: Re: worded question :@
Post by: TrueTears on February 28, 2010, 05:02:57 pm: its ok.
Title: Re: worded question :@
Post by: cindyy on February 28, 2010, 05:06:53 pm: wait, i just did it again, isnt it supposed to be 9 +10
:S How did you get 12 + 13?
Title: Re: worded question :@
Post by: the.watchman on February 28, 2010, 05:07:25 pm: Quote from: cindyy on February 28, 2010, 05:06:53 pm
wait, i just did it again, isnt it supposed to be 9 +10
:S How did you get 12 + 13?

Lol, check again, I've changed it :D
Title: Re: worded question :@
Post by: mandy on February 28, 2010, 05:07:47 pm: It is 9 and 10, I think he just fixed it or something.
Title: Re: worded question :@
Post by: the.watchman on February 28, 2010, 05:08:29 pm: Quote from: mandy on February 28, 2010, 05:07:47 pm
It is 9 and 10, I think he just fixed it or something.

I fixed it about a minute after posting, I forgot the 1/4 on the left hand side :P
Title: Re: worded question :@
Post by: cindyy on February 28, 2010, 05:08:52 pm: greatgreat :)