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bobAlike
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« on: January 15, 2012, 12:34:28 PM » |
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Having not studied Maths for well over 20 years my 12 year old lad asked me for some help with his homework.
The question is:
Jen is y years old and her mother is 27 years older. Together their ages total 45 years.
a. In terms of Jen's age, how old is her mother now?
b. Form an equation in y and solve it to find Jen's age and her mother's age now.
He knows the ages are 9 and 36 but is struggling with forming the equation and Im just brain dead today.
Any help appreciated.
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Ah! The element of surprise
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Cf
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« Reply #1 on: January 15, 2012, 12:38:55 PM » |
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a) y + 27
b) y + (y+ 27) = 45
2y = 18
y = 9
And the mother is 36 based on a)
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bobAlike
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« Reply #2 on: January 15, 2012, 12:43:32 PM » |
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a) y + 27
b) y + (y+ 27) = 45
2y = 18
y = 9
And the mother is 36 based on a)
Tyvm |
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Ah! The element of surprise
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bobAlike
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« Reply #3 on: January 15, 2012, 12:58:12 PM » |
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One more please.
Question:
Sonia is n years old now and Cynthia, her sister, is 2 years older. In 5 years time the sum of their ages will be 20.
How old is Sonia now?
How old will Cynthia be in 5 years time?
Again he knows the answers but not the equations to get to the answers.
Thanks
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Ah! The element of surprise
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Cf
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« Reply #4 on: January 15, 2012, 01:04:35 PM » |
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In 5 years time:
n + (n+2) = 20
2n + 2 = 20
2n = 18
n = 9 (Sonia)
Cynthia = 11 (n + 2)
Now:
5 years earlier so Sonia is 4.
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bobAlike
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« Reply #5 on: January 15, 2012, 01:06:04 PM » |
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In 5 years time:
n + (n+2) = 20
2n + 2 = 20
2n = 18
n = 9 (Sonia)
Cynthia = 11 (n + 2)
Now:
5 years earlier so Sonia is 4.
Thanks again |
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Ah! The element of surprise
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Jon MW
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« Reply #6 on: January 15, 2012, 01:07:11 PM » |
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sigh - was going to do some teaching but CF was too quick with just the answer
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Jon "the British cowboy" Woodfield
2011 blonde MTT League August Champion
2011 UK Team Championships: Black Belt Poker Team Captain - - runners up - -
5 Star HORSE Classic - 2007 Razz Champion
2007 WSOP Razz - 13/341
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bobAlike
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« Reply #7 on: January 15, 2012, 01:08:18 PM » |
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sigh - was going to do some teaching but CF was too quick with just the answer
Feel free to eloborate |
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Ah! The element of surprise
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Jon MW
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« Reply #8 on: January 15, 2012, 01:12:30 PM » |
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sigh - was going to do some teaching but CF was too quick with just the answer
Feel free to eloborate Knowing the answer means it doesn't really work after the fact But basically the formula is just constructed from the words. Take the words like age (n),her sister is two years older (so n+2) - you then build up the rest of the formula following the words so that = 20, then you take off 5 because that's in 5 years time. Like I suggested, it seems a bit obvious just spelling it out like that once you've seen the answer - people can kind of remember stuff by it being explained, but you really learn by working it out yourself. |
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Jon "the British cowboy" Woodfield
2011 blonde MTT League August Champion
2011 UK Team Championships: Black Belt Poker Team Captain - - runners up - -
5 Star HORSE Classic - 2007 Razz Champion
2007 WSOP Razz - 13/341
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the sicilian
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« Reply #9 on: January 15, 2012, 01:15:03 PM » |
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This is fantastic.... Celticalike has got u to do his lads homework and he looks like a genius in his child's eyes... Nice moves bobo
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Just because you don't like it...... It doesn't mean it's not the truth
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Cf
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« Reply #10 on: January 15, 2012, 01:21:11 PM » |
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Has this one been done on here before?
I have a standard coin. But... it is biased to one side. We don't know which side, nor do we know the size of the bias. How can we use this coin to get a genuine 50/50 chance?
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bobAlike
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« Reply #11 on: January 15, 2012, 01:23:10 PM » |
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sigh - was going to do some teaching but CF was too quick with just the answer
Feel free to eloborate Knowing the answer means it doesn't really work after the fact But basically the formula is just constructed from the words. Take the words like age (n),her sister is two years older (so n+2) - you then build up the rest of the formula following the words so that = 20, then you take off 5 because that's in 5 years time. Like I suggested, it seems a bit obvious just spelling it out like that once you've seen the answer - people can kind of remember stuff by it being explained, but you really learn by working it out yourself. I totally agree with your sentiments on learning. I just couldnt elaborate on it for my lad. Unbelievably I was kid genius at Maths and was put up for A level at 13. I just have not done anything significant in numbers since I was 18, 26 years ago. I used to love numbers and recently bought a book called 'Alex's adventures in number land' excellent read if anyone's interested. |
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Ah! The element of surprise
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bobAlike
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« Reply #12 on: January 15, 2012, 01:24:14 PM » |
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This is fantastic.... Celticalike has got u to do his lads homework and he looks like a genius in his child's eyes... Nice moves bobo
Lol, lad sitting next to me and knows his dads a fraud. |
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Ah! The element of surprise
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AndrewT
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« Reply #13 on: January 15, 2012, 04:12:28 PM » |
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Has this one been done on here before?
I have a standard coin. But... it is biased to one side. We don't know which side, nor do we know the size of the bias. How can we use this coin to get a genuine 50/50 chance?
Do the thing where you hide it in one hand and get someone else to guess which hand it is in. |
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Cf
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« Reply #14 on: January 15, 2012, 04:24:25 PM » |
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Nope. Too many other factors for that to be 50/50.
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