imaqtz
Forum God
I am a Condor.
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Registration Date: 17-07-2001
Posts: 1049
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21-07-2004 18:26
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lyon
Boardie
I am an Eagle.
4 fics uploaded
Registration Date: 06-12-2002
Posts: 287
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grin .. i loved math. i dont find a use for it now but these sort of stumpers always made me scritch my head and try to figure out how to cheat the system and still come up with the correct answer.
the first two .. the point A, point B ones are sneaky .. they make you think they're more complicated than they are. let's take the first.
Driving from point A to point B at 33km/h takes 2 hours less than cycling at 11km/h..How far is it between A and B?
this can be expressed as two lines and all you have to do is figure out where you have a two hour difference.
car: |----------|----------|----------|||
bike: |----------||
in the first hour (denoted above) the car travels 33km - the bicycle only travels 11km (1/3 the distance). In order to travel to the 33km mark, the bicycle is going to have to travel another two hours to reach the same distance. by this time the car will be long gone into the next country but that's besides the point - problem solved, the answer is 33 km between point A and B.
Mary walked from point A and B at 6km/h and returned at 4 km/h. It took her 5 hours. How far was it from A to B?
i love this one .. because its easy as pie once you know how to look at it. Mary was an idiot and realised she'd left her favorite comic book at her friend's house. She ran there as fast as she could before her friend could destroy her beloved property, grabbed the comic and walked home again with aching feet and a lighter heart. the key here is that the distance there and back is the same.
Mary's House ---------x----------- Friend's House ---------x----------- Mary's House
all you have to do is figure out when the distances vs hours match .. and its dead easy. you have to make a combined total of five hours. She ran for two hours to get there (6km + 6km = 12) and walked for 3 hours (4km +4km +4km=12) to get home. Therefore her friend's house is 12km away.
If a solution weighs 200grams and consists of 8 grams of salt, the solution is called a 4% salt solution. If a slutions weighs 300 grams and consits of 6 grams of slat..then what percentage salt solution is it?
ah, percentages. this is easy stuff since its all fractions. reduce both sides of the equation by a common denominator in order to get a yield of (100) on the bottom of the equation on one side - this will give you a percentage solution (in this case reduce 8/200 in half to yield 4/100)
8 (grams salt).............divided by 2...... = 4 (g salt)
---- -----
200 (grams solution)...divided by 2.......= 100 (g solution) = 4% solution
therefore:
6
----- ....= ? %
300
-- divide the bottom number (300) by 3 in order to get a (100%) solution, and divide the top number by the same factor of 3 which will give you:
2
-----....= 2% solution
100
We have 500 grams of 10% salt solution. How many grams of water must be added to dilute the solution to form a 4% solution?
this is two questions. first you have to find out how many grams of salt there are in the solution: using the thingies above, the first equation is thus. (10% is expressed as 10 / 100.)
? (grams salt) ............................( 10 )
------ ...........................= 10%....... -----
500 (grams solution)....................( 100 )
in order to find out how many grams of salt you have (since you don't know) all you have to do is figure out how much you have to multiply 100 by, in order to get 500 (easy, huh? a factor of 5). 10 x 5 = 50grams of salt. this was called "cross multiply and divide" in my school - take the top figure you know muliplied by the bottom figure that is also known, and then divide by the remaining number to solve for the unknown value.
okay, so our solution holds 50grams of salt. how much solution do we need to add to get a 4% solution?
50..........4
------.=.-----
?.........100
so cross multiply and divide to solve the equation : 50 x 100 = 5000 divided by 4 (the remaining value) = 1250 grams of solution required to make the 4% solution. it started with 500grams of solution already, so you'd need to add an additional 750grams of water.
man, i haven't done any of this stuff since high school! let's do a logic puzzle now!
__________________
Trample the weak. Hurdle the dead.
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22-07-2004 02:08
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CricketBeautiful
Forum God
I am a Zark.
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Registration Date: 04-04-2004
Posts: 1211
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We lucked out -- Dad is electrical engineer, in R&D. But he learned in the 1950s. They'd changed the methods twice since then, so when I had a problem, I had to translate his solution. Mom was good, though -- laid things out well.
But I had this real block about electicity -- anything more complicated than the basic flashlight and the pipeline analogy, and I blocked.
Worst day in school ever was when, in fluid dynamics, they said, "and, the electricals do this all the time, so we'll use the electrical analogy".
If you want two more ways to solve the solutions problem, just ask. And if you want even more chemicals involved, it'll be a good refresher. Might just do it on paper and scan it, though.
Cheers!
__________________
Between stimulus and response there is a space.
In that space is our power to choose our response.
In our response lies our growth and our freedom.
- Viktor E. Frankl
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22-07-2004 19:37
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imaqtz
Forum God
I am a Condor.
0 fics uploaded
Registration Date: 17-07-2001
Posts: 1049
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| quote: | | man, i haven't done any of this stuff since high school! let's do a logic puzzle now! |
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You ASKED for it!!.. 
Ill donate 200 of my gatch dollars for each lateral thinking problem solved, to anyone who can figure these out.!!.
1) There is a man that lives on the top floor of a very tall building.
Everyday he gets the elevator down to the ground floor to leave
the building to go to work. Upon returning from work though, he
can only travel half way up in the lift and has to walk the rest of
the way unless it's raining!
- WHY?
2) A man and his son are in a car accident. The father dies on
the scene, but the child is rushed to the hospital. When he arrives
the surgeon says, "I can't operate on this boy, he is my son!"
- How can this be?
3) A man is wearing black. Black shoes socks, trousers, shirt,
gloves and coat. He is walking down a black street with all the
street lamps off. A black car is coming towards him with its light off
too but somehow manages to stop in time.
- How did the driver see the man?
4) Title: The Elder Twin One day Kerrie celebrated her birthday. Two days
later her older twin brother, Terry, celebrated his birthday.
- Why?
5) Title: Manhole Covers
Why is it better to have round manhole covers than square ones?
6) Title: Heaven
A man died and went to Heaven. There were thousands of other people there.
They were all naked and all looked as they did at the age of 21. He looked
around to that see if there was anyone he recognized. He saw a couple and
he
knew immediately that they were Adam and Eve.
- How did he know?
7)Title: Trouble with Sons
A woman had two sons who were born on the same hour of the same day of the
same year. But they were not twins. How could this be so?
 Title: The Man in the Bar A man walks into a bar and asks the barman for
a
glass of water. The barman pulls out a gun and points it at the man. The
man
says 'Thank you' and walks out.
__________________
Shoot first..ask questions later!
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08-08-2004 14:48
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