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Re: Maths Tricks, Questions And Brain Teasers by ektbear: 5:31pm On Nov 27, 2012 |
shymexx: 1. For the specific choice I gave, yes. But of course, where exactly the point is will depend on his position. 2. Keep in mind that the problem doesn't ask you to provide the intersection point (i.e., where on the hill this event happens). It just asks, "Does there exist such a time?" |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 5:40pm On Nov 27, 2012 |
ekt_bear: Obviously, such a time would exist since he has to go through the same path on both days... However, the time he takes to walk the path on both days and the distance between his house and the hill aren't given, then the most likely time has to be the entry/exit point... You also have to put the "constant" into consideration... |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 5:40pm On Nov 27, 2012 |
If: x(t) = t^2, y(t) = 1-t x(t)=y(t) t^2=1-t t^2+t-1=0 t= (-1-sqrt(1+4))/2 impossible since time cannot be negative t= (-1+sqrt(1+4))/2 = 0.618 ? |
Re: Maths Tricks, Questions And Brain Teasers by ektbear: 5:50pm On Nov 27, 2012 |
Sybellah: Yes ma'am. You clearly remember your high school mathematics well Hmm. I'm now intrigued more by you... |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 6:06pm On Nov 27, 2012 |
ekt_bear and sybellah Use the same method to solve this: Some friends on a hike leave at 9am and return at 2pm. They spend one-quarter of the total distance walking uphill, one-half walking on level ground, and one-quarter walking downhill. if their speed is 4mph on level ground, 2 mph uphill, and 6 mph downhill,approximately how far did they walk? A. 16.9 miles B. 17.2 miles C. 10.6 miles D. 15.3 E. None of these. |
Re: Maths Tricks, Questions And Brain Teasers by ektbear: 6:33pm On Nov 27, 2012 |
None, I believe. If you let s1 = 4, s2=2, s3=6, and D denote the unknown distance they travel, we need for: (2pm-9am) = 5 = D*(0.25/s1 + 0.5/s2 + 0.25/s3). Plugging in and solving, this gives D=14.117. So unless I've made a dumb algebra mistake, then the answer is none. |
Re: Maths Tricks, Questions And Brain Teasers by LordReed(m): 6:53pm On Nov 27, 2012 |
@ekt_bear Na wa for this your mathematical conundrum o! We even need buy graph paper to take answer am. ℓ☺ℓ |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 6:58pm On Nov 27, 2012 |
Ekt The answer is B... I was just trying to show you and sybellah that the method you guys used is flawed... That was why I wanted you guys to use the same method to solve a similar puzzle albeit with more information... This is maths, you don't just use "undefined terms" to solve a puzzle - that would amount to guess work than anything else, no matter how you present it... The 0.618 answer for your puzzle is BOGUS! Solution to my question: time = 5 total distance = x 0.25x = walking uphill 0.50x = walking on level ground 0.25x = walking downhill walking uphill = 2mph walking on level ground = 4mph walking downhill = 6mph 0.25x/2 + 0.50x/4 + 0.25/6 = 5 ... note "/" denotes distance x by velocity/speed (1.50x + 1.50x + 0.50x)/12 = 5 3.50x/12 = 5 3.50x = 60 x = 60/3.50 = 17.20miles = B |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 7:08pm On Nov 27, 2012 |
shymexx: Ekt hum huum ok I understand |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 7:12pm On Nov 27, 2012 |
ekt_bear: None, I believe. but this is the same method Shymmex used right? 5= if u multiply the d by every term in the parenthesis...u probably made some algebra mistake let say x=d 5= d*(0.25/s1) + d*(0.5/s2) + d*(0.25/s3) 5= d*(0.25/4) + d*(0.5/2) + d*(0.25/6) put it at the same denom 12....u find a similar answer |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 7:13pm On Nov 27, 2012 |
Sybellah: More reason why the ans to ekt_bear's question has to be 1(the point of exit/entry)... Anything outside that is bogus!! You don't even need algebra for it, your cognitive skills alone should answer the question... |
Re: Maths Tricks, Questions And Brain Teasers by ektbear: 7:15pm On Nov 27, 2012 |
Ah, you are right. I didn't read this sentence carefully: "hey spend one-quarter of the total distance walking uphill, one-half walking on level ground, and one-quarter walking downhill. if their speed is 4mph on level ground, 2 mph uphill, and 6 mph downhill,approximately how far did they walk?" I assumed that you were using the same ordering when reporting the numbers...didn't notice that you changed it. |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 7:17pm On Nov 27, 2012 |
nono guys wait i think its the same calculations u made, but it's structured differently |
Re: Maths Tricks, Questions And Brain Teasers by ektbear: 7:17pm On Nov 27, 2012 |
Sybellah: He stated uphill, level ground, then downhill, then stated level ground, uphill, downhill in the second part. So if you assume the same order like I did and don't read very carefully, you'll use wrong #s. |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 7:17pm On Nov 27, 2012 |
Sybellah: Why should I multiply D by every term in the bracket? |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 7:20pm On Nov 27, 2012 |
shymexx: lol, mad face of math teacher ready to slap |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 7:20pm On Nov 27, 2012 |
Ekt Do you now agree that I got the answer to your puzzle? |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 7:21pm On Nov 27, 2012 |
kk i see now |
Re: Maths Tricks, Questions And Brain Teasers by ektbear: 7:22pm On Nov 27, 2012 |
shymexx: Ekt no, your answer of 9am is flat out wrong. it doesn't even make any sense, unless the ijebu man has some sort of teleportation device |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 7:27pm On Nov 27, 2012 |
no but here it was a reading mistakes, but the method was the same the mistakes were at this level (2pm-9am) = 5 = D*(0.25/s1 + 0.5/s2 + 0.25/s3). 5= d*(0.25/4) + d*(0.5/2) + d*(0.25/6) correcting this would be 0.25*d/2 + 0.50*d/4 + 0.25*d/6 = 5 which is the same as this 0.25x/2 + 0.50x/4 + 0.25/6 = 5 no? |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 7:28pm On Nov 27, 2012 |
ekt_bear: The distance to and from the hill to his house is irrelevant, since it's not defined... Only the constant(9am) is relevant - that's how mathematical tricks work.. The answer is either 0((his house) or 1(point of entry/exit at the hill).. And since "9am" is the constant in both "0" and "1", then that should be the answer... |
Re: Maths Tricks, Questions And Brain Teasers by ektbear: 7:29pm On Nov 27, 2012 |
Sybellah: no but here it was a reading mistakes, but the method was the same You are correct. |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 7:30pm On Nov 27, 2012 |
Sybellah: no but here it was a reading mistakes, but the method was the same Yep.. |
Re: Maths Tricks, Questions And Brain Teasers by ektbear: 7:30pm On Nov 27, 2012 |
shymexx: Bros. Suppose the hill is 1000 miles high. He left his house 9am on Monday. He leaves the top of the hill 9am Tuesday to go back home. Are you really saying that at 9am on Tuesday he is back home? 0 seconds after he decided to leave the top of the hill? This Ijebu man, unless he has a teleportation device or strong juju will not be able to do that |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 7:34pm On Nov 27, 2012 |
ekt_bear: I understand where you're coming from, however, the distance wasn't defined in the puzzle, was it? So, you can't really give it a value based on assumptions... It could be 1000 miles high, or 0.0001 miles high, but we'll never know... |
Re: Maths Tricks, Questions And Brain Teasers by ektbear: 7:36pm On Nov 27, 2012 |
Well, the hill doesn't have a height of zero. If you weren't sure whether values of 0 for the height of the hill are alowed, just ask. And assuming that the hill has height greater than zero, then 9am won't be the answer (again, also assuming no juju or teleportation devices). The only thing you need to know is that the hill doesn't have height zero. |
Re: Maths Tricks, Questions And Brain Teasers by ektbear: 7:37pm On Nov 27, 2012 |
anyway i got to get some work done. talk to you guys later |
Re: Maths Tricks, Questions And Brain Teasers by Nobody: 8:38pm On Nov 27, 2012 |
kk ttyl |
Re: Maths Tricks, Questions And Brain Teasers by LordReed(m): 9:54pm On Nov 27, 2012 |
@ekt_bear Hmmm, seems we shall have to start a Nairaland College of Riddle Solving. LMAO |
Re: Maths Tricks, Questions And Brain Teasers by somegirl1: 12:08am On Nov 28, 2012 |
ekt_bear please answer your original question without assuming there are two men intersecting. Q: |
Re: Maths Tricks, Questions And Brain Teasers by ektbear: 12:53am On Nov 28, 2012 |
1. The two men ONLY came into place because I transformed from the original problem into one of two different men. Do you not get how the two men problem is equivalent to the original? This is the key to the whole matter. So clarify if it doesn't make sense to you. 2. Regarding the intersection of the two men, given that you are told in the original problem that the man uses the same path, necessarily then in the two man problem they must eventually run into each other. |
Re: Maths Tricks, Questions And Brain Teasers by somegirl1: 1:04am On Nov 28, 2012 |
ekt_bear: 1. The two men ONLY came into place because I transformed from the original problem into one of two different men. Do you not get how the two men problem is equivalent to the original? This is the key to the whole matter. So clarify if it doesn't make sense to you. oh dear, I think I'll just drop it as I can't seem to get it across to you that asking for a point of intersection is different from your original question. I'll take it as a miscommunication. |
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