thill@ssc-bee.UUCP (Tom Hill) (03/08/85)
Here is a good interview problem. It can be a bit heartless to give to a nervous interviewee but bewarned... a guy I met was actually asked this! You have to travel from town A. to town B. The distance between the two towns is 2 miles. If you drive 30 mph for the first mile, how fast do you have to drive the second mile in order to average 60 mph? It can be tricky if you don't think about it. Tom Hill
joe@petsd.UUCP (Joe Orost) (03/09/85)
Distribution: Organization: Perkin-Elmer DSG, Tinton Falls, N.J. Keywords: In article <302@ssc-bee.UUCP> thill@ssc-bee.UUCP (Tom Hill) writes: > You have to travel from town A. to town B. The distance > between the two towns is 2 miles. If you drive 30 mph for the > first mile, how fast do you have to drive the second mile in > order to average 60 mph? > >It can be tricky if you don't think about it. Your right about that. I thought about it and here is the answer: It can't be done. Explanation: In order to average 60 mph, you must travel 1 mile in 1 minute. Therefore, you must travel the 2 miles in 2 minutes. But, you have already taken 2 minutes to travel the first mile, so even if you go "faster than greased lightning" in the second mile, you won't make the 60mph average.
ronbe@tekred.UUCP (Ron Bemis ) (03/09/85)
> You have to travel from town A. to town B. The distance > between the two towns is 2 miles. If you drive 30 mph for the > first mile, how fast do you have to drive the second mile in > order to average 60 mph? Real fast... If you drive the first mile at 30 mph, you've already blown your two minutes needed to average 60 mph. -- tektronix!tekred!ronbe _____ Support Bacteria - Ron Bemis / o o \ It's the only Tektronix | \___/ | culture some Redmond, OR \_____/ people have!
peterb@pbear.UUCP (03/10/85)
If you don't want the answer, hit n now. . . . . . . . . . . . . . . . . . . Ok, The problem: town a to town b is two miles. first mile is travelled at 30 mph question: what speed is needed to average 60 mph. First mile is travelled at 30 mph, or 2 minute miles. 2 miles@60 is 2 minutes, so no matter what speed you travel at, you can not get 60mph average. So if you are asked this question (as I was in an interview), some possible answers to keep in your head are: 1) Indeterminate. (division by 0) 2) Infinite. 3) What do I care, math and marketing don't mix! :-) Peter Barada ima!Pbear!peterb
mrh@cybvax0.UUCP (Mike Huybensz) (03/10/85)
In article <302@ssc-bee.UUCP> thill@ssc-bee.UUCP (Tom Hill) writes: > Here is a good interview problem. It can be a bit heartless to give > to a nervous interviewee but bewarned... a guy I met was actually > asked this! > > You have to travel from town A. to town B. The distance > between the two towns is 2 miles. If you drive 30 mph for the > first mile, how fast do you have to drive the second mile in > order to average 60 mph? There are two simple answers. a) You cannot travel fast enough. You have already consumed the entire two minutes required to average 60 mph over the time it takes to make the trip. b) 90 mph. You will then have travelled an average of 60 mph over the DISTANCE of the trip. There probably are other measures possible as well. -- Mike Huybensz ...decvax!genrad!mit-eddie!cybvax0!mrh
ncg@ukc.UUCP (N.C.Gale) (03/11/85)
In article <302@ssc-bee.UUCP> thill@ssc-bee.UUCP (Tom Hill) writes: > > >Here is a good interview problem. It can be a bit heartless to give >to a nervous interviewee but bewarned... a guy I met was actually >asked this! > > > > You have to travel from town A. to town B. The distance > between the two towns is 2 miles. If you drive 30 mph for the > first mile, how fast do you have to drive the second mile in > order to average 60 mph? > > >It can be tricky if you don't think about it. > > >Tom Hill average? average over what? Time? Distance? Speed(?)? 8-( Nige Gale
ndiamond@watdaisy.UUCP (Norman Diamond) (03/11/85)
> Here is a good interview problem. > You have to travel from town A. to town B. The distance > between the two towns is 2 miles. If you drive 30 mph for the > first mile, how fast do you have to drive the second mile in > order to average 60 mph? > -- Tom Hill It is an excellent interview question. By watching the applicant's reaction, the interviewer can predict how the applicant would perform on the job when typical users or managers make typical demands.... -- Norman Diamond UUCP: {decvax|utzoo|ihnp4|allegra}!watmath!watdaisy!ndiamond CSNET: ndiamond%watdaisy@waterloo.csnet ARPA: ndiamond%watdaisy%waterloo.csnet@csnet-relay.arpa "Opinions are those of the keyboard, and do not reflect on me or higher-ups."
vch@rruxo.UUCP (V. Hatem) (03/12/85)
let's be real - you people are actually posting ANSWERS to that question?? I'd be ashamed if I couldn't answer that question! (what makes you think anybody is THAT stupid??? Vince.
ron@brl-tgr.ARPA (Ron Natalie <ron>) (03/12/85)
My favorite is: Why are manhole covers round? There are two answers.
vch@rruxo.UUCP (V. Hatem) (03/12/85)
If you were asked that question during an interview, you may be able to sue, as it is illegal in many states to ask questions like that during an interview! (something about discrimination...) vince.
ndiamond@watdaisy.UUCP (Norman Diamond) (03/12/85)
> let's be real - you people are actually posting ANSWERS to that question?? > I'd be ashamed if I couldn't answer that question! (what makes you think > anybody is THAT stupid??? > > Vince. So, anyone who didn't concentrate in communications theory (or related areas of applied mathematics) should not be using the net, eh? We are all stupid, eh? Anyone who was interested in compiler design, mulitprocessing protocols, set theory, etc., is stupid, stupid, stupid! -- Norman Diamond UUCP: {decvax|utzoo|ihnp4|allegra}!watmath!watdaisy!ndiamond CSNET: ndiamond%watdaisy@waterloo.csnet ARPA: ndiamond%watdaisy%waterloo.csnet@csnet-relay.arpa "Opinions are those of the keyboard, and do not reflect on me or higher-ups."
bulko@ut-sally.UUCP (William C. Bulko) (03/13/85)
< bug off! >
In response to the question, "Why are manhole covers round?" : I learned
that it was because the circle is the only two-dimensional shape that has
the same diameter no matter how you turn it. (The square, for example,
is smaller when viewed from one side than when viewed from a corner, since
a diagonal is longer than a side.) The implication is that a manhole cover
cannot accidentally fall through the manhole and injure someone below, where
any other shape could.
There's a second reason? I'd guess that it would be that since manhole
covers are so heavy, it's easier to roll them than to carry them!
Do I win?
--
_______________________________________________________________________________
"To err is human; to admit it is not."
Bill Bulko Department of Computer Sciences
The University of Texas {ihnp4,harvard,gatech,ctvax,seismo}!ut-sally!bulko
_______________________________________________________________________________john@x.UUCP (John Woods) (03/13/85)
> My favorite is: > > Why are manhole covers round? > > There are two answers. > Simple. If they were square, only managers could fit them over the hole. -- John Woods, Charles River Data Systems, Framingham MA, (617) 626-1101 ...!decvax!frog!john, ...!mit-eddie!jfw, jfw%mit-ccc@MIT-XX.ARPA Sorry, I don't feel deep right now.
sdi@loral.UUCP () (03/13/85)
In article <463@petsd.UUCP> joe@petsd.UUCP (PUT YOUR NAME HERE) writes: >Distribution: >Organization: Perkin-Elmer DSG, Tinton Falls, N.J. >Keywords: > >In article <302@ssc-bee.UUCP> thill@ssc-bee.UUCP (Tom Hill) writes: >> You have to travel from town A. to town B. The distance >> between the two towns is 2 miles. If you drive 30 mph for the >> first mile, how fast do you have to drive the second mile in >> order to average 60 mph? >> >>It can be tricky if you don't think about it. > >Your right about that. I thought about it and here is the answer: > > It can't be done. > >Explanation: In order to average 60 mph, you must travel 1 mile in 1 minute. >Therefore, you must travel the 2 miles in 2 minutes. But, you have already >taken 2 minutes to travel the first mile, so even if you go "faster than >greased lightning" in the second mile, you won't make the 60mph average. *********** Question: The original question says nothing about time. Why can't you go 30mph for the first mile and 90mph for the second mile, therefore averaging out to 60mph. If you are driving along going 30mph for 1 mile and then 90mph in the next, you are averaging 60mph for the 2 miles. Am I missing something here?
scottp@tekig1.UUCP (Scott Phillips) (03/14/85)
> Distribution: > Organization: Perkin-Elmer DSG, Tinton Falls, N.J. > Keywords: > > In article <302@ssc-bee.UUCP> thill@ssc-bee.UUCP (Tom Hill) writes: > > You have to travel from town A. to town B. The distance > > between the two towns is 2 miles. If you drive 30 mph for the > > first mile, how fast do you have to drive the second mile in > > order to average 60 mph? > > > >It can be tricky if you don't think about it. > > Your right about that. I thought about it and here is the answer: > > It can't be done. > > Explanation: In order to average 60 mph, you must travel 1 mile in 1 minute. > Therefore, you must travel the 2 miles in 2 minutes. But, you have already > taken 2 minutes to travel the first mile, so even if you go "faster than > greased lightning" in the second mile, you won't make the 60mph average. ah, but if you exceed the speed of light, you can stop the advance of time (relative to you). For that matter, you can arrive yesterday, the day before, or the year before; dependent on how much you exceeded the speed of light.
halle@hou2b.UUCP (J.HALLE) (03/14/85)
There is a shape other than a circle which would prevent the manhole cover from falling through. What is it?
ndiamond@watdaisy.UUCP (Norman Diamond) (03/15/85)
> *********** > Question: The original question says nothing about time. Why can't you go > 30mph for the first mile and 90mph for the second mile, therefore averaging > out to 60mph. If you are driving along going 30mph for 1 mile and then > 90mph in the next, you are averaging 60mph for the 2 miles. Am I missing > something here? Speed does say something about time and distance. You average 30mph for the first mile, 90mph for the second mile, and 45mph for the total two miles. Alternatively: you average 30mph for the first 120 seconds, 90mph for the next 40 seconds, and 45mph for the total 160 seconds. (If you don't believe this one, take the mean of 30, 30, 30, and 90. If you still don't believe it, then take the mean of 1, 1, 1, 1, 1, 1, 1, 1, 1, and 1001; it is not 501.) -- Norman Diamond UUCP: {decvax|utzoo|ihnp4|allegra}!watmath!watdaisy!ndiamond CSNET: ndiamond%watdaisy@waterloo.csnet ARPA: ndiamond%watdaisy%waterloo.csnet@csnet-relay.arpa "Opinions are those of the keyboard, and do not reflect on me or higher-ups."
ron@brl-tgr.ARPA (Ron Natalie <ron>) (03/15/85)
> There is a shape other than a circle which would prevent the manhole > cover from falling through. What is it? There are several. Triangle, pentagon, etc... By the way, the two answers I was looking for were: 1. So it won't fall in. 2. Because manholes are round. -Ron
emh@bonnie.UUCP (Edward M. Hummel) (03/16/85)
>There is a shape other than a circle which would prevent the manhole >cover from falling through. What is it? An equilateral triangle . ----------------------------------------------- Ed Hummel ...!clyde!bonnie!emh
ron@brl-tgr.ARPA (Ron Natalie <ron>) (03/17/85)
> Question: The original question says nothing about time. Why can't you go > 30mph for the first mile and 90mph for the second mile, therefore averaging > out to 60mph. If you are driving along going 30mph for 1 mile and then > 90mph in the next, you are averaging 60mph for the 2 miles. Am I missing > something here? Your average speed would be: Distance Traveled (miles) -------------------------- Time Taken (hours) which is to say (First Mile) + (Second Mile) average speed = ---------------------------------------------- (Time for first mile) + (Time for second mile) Putting in some numbers 2 60 = ------------------------------------------------- (1/30) + (time for second mile) since the total distance is two miles, you want the average speed to be 60 mph and it took you 2 minutes (1/30 of an hour) to do the first mile. Solve and find that (time for second mile) = 0 Which means you must travel one mile in no time at all. -Ron
gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>) (03/17/85)
> >> You have to travel from town A. to town B. The distance > >> between the two towns is 2 miles. If you drive 30 mph for the > >> first mile, how fast do you have to drive the second mile in > >> order to average 60 mph? > Question: The original question says nothing about time. Why can't you go > 30mph for the first mile and 90mph for the second mile, therefore averaging > out to 60mph. If you are driving along going 30mph for 1 mile and then > 90mph in the next, you are averaging 60mph for the 2 miles. Am I missing > something here? Yes. Just because you can add two numbers and divide by two does not mean that you have thereby produced a physically meaningful "average". You might as well say that the "average distance" is (1 + 1) / 2 = 1 mile! Average speed = Total path length / Total travel time
wws@whuxlm.UUCP (Stoll W William) (03/17/85)
> > There is a shape other than a circle which would prevent the manhole > > cover from falling through. What is it? > > There are several. > Triangle, pentagon, etc... > I disagree that triangles and pentagons couldn't fall through. If you stand them flat on one of their sides, the height will always be less than if you pivot them (slightly) on a vertex. Can anyone express this mathematically? -- I was never the geometry wizard. Bill Stoll, ..!whuxlm!wws
ndiamond@watdaisy.UUCP (Norman Diamond) (03/18/85)
> > There is a shape other than a circle which would prevent the manhole > > cover from falling through. What is it? > > There are several. > Triangle, pentagon, etc... > -Ron Triangles and pentagons WILL fall through if oriented appropriately. Sicherman's solutions (already posted, based on an article by Martin Gardner, originally due to ????) are correct answers. -- Norman Diamond UUCP: {decvax|utzoo|ihnp4|allegra}!watmath!watdaisy!ndiamond CSNET: ndiamond%watdaisy@waterloo.csnet ARPA: ndiamond%watdaisy%waterloo.csnet@csnet-relay.arpa "Opinions are those of the keyboard, and do not reflect on me or higher-ups."
ron@brl-tgr.ARPA (Ron Natalie <ron>) (03/18/85)
> > > There is a shape other than a circle which would prevent the manhole > > > cover from falling through. What is it? > > > > There are several. > > Triangle, pentagon, etc... > > > > I disagree that triangles and pentagons couldn't fall through. Your right, it's been demostrated to me. The height of the triangle (even an equilateral one is 15% smaller than the edge. -Ron
williamg@nmtvax.UUCP (03/20/85)
>In article <302@ssc-bee.UUCP> thill@ssc-bee.UUCP (Tom Hill) writes: >> You have to travel from town A. to town B. The distance >> between the two towns is 2 miles. If you drive 30 mph for the >> first mile, how fast do you have to drive the second mile in >> order to average 60 mph? >>It can be tricky if you don't think about it. >You're right about that. I thought about it and here is the answer: > It can't be done. >Explanation: In order to average 60 mph, you must travel 1 mile in 1 minute. >Therefore, you must travel the 2 miles in 2 minutes. But, you have already >taken 2 minutes to travel the first mile, so even if you go "faster than >greased lightning" in the second mile, you won't make the 60mph average. Ah, but if you travel at 186,000 mps you WILL make it. Why? lim t = 0 {limit of t as velocity goes to the speed of light = 0} v>c ask a physicist to explain. -- Lawn Care, Shred {lanl!unmvax!unm-cvax!nmtvax!williamg} [The opinions expressed herein are my own. Permission for publication granted.] "Computer theft is a crime! Prosecuters will be violated."
drseuss@nmtvax.UUCP (03/20/85)
> >Va negvpyr <302@ffp-orr.HHPC> guvyy@ffp-orr.HHPC (Gbz Uvyy) jevgrf: > >> Lbh unir gb geniry sebz gbja N. gb gbja O. Gur qvfgnapr > >> orgjrra gur gjb gbjaf vf 2 zvyrf. Vs lbh qevir 30 zcu sbe gur > >> svefg zvyr, ubj snfg qb lbh unir gb qevir gur frpbaq zvyr va > >> beqre gb nirentr 60 zcu? > >>Vg pna or gevpxl vs lbh qba'g guvax nobhg vg. > >Lbh'er evtug nobhg gung. V gubhtug nobhg vg naq urer vf gur nafjre: > > Vg pna'g or qbar. > >Rkcynangvba: Va beqre gb nirentr 60 zcu, lbh zhfg geniry 1 zvyr va 1 zvahgr. > >Gurersber, lbh zhfg geniry gur 2 zvyrf va 2 zvahgrf. Ohg, lbh unir nyernql > >gnxra 2 zvahgrf gb geniry gur svefg zvyr, fb rira vs lbh tb "snfgre guna > >ternfrq yvtugavat" va gur frpbaq zvyr, lbh jba'g znxr gur 60zcu nirentr. > Nu, ohg vs lbh geniry ng 186,000 zcf lbh JVYY znxr vg. Jul? > yvz g = 0 {yvzvg bs g nf irybpvgl tbrf gb gur fcrrq bs yvtug = 0} > i>p > nfx n culfvpvfg gb rkcynva. > -- > Ynja Pner, > Fuerq ------------------------------------------------------------------------------- Qba'g lbh whfg ungr arjpbzref?! By' Ovyy, guvf dhrfgvba naq vgf fbyhgvba unf orra nebhaq sbe dhvgr fbzr gvzr abj. Jurer gur uryy unir lbh orra, ohq? Bx. Abj sbe n wbxr... Yvggyr Zvff Zhssrg fng ba ure ghssrg rngvat ure pheqf naq junl, nybat pnzr n fcvqre naq fng qbja orfvqr ure naq fur cvpxrq hc n fcbba naq orng gur fuvg bhg bs vg! (cyrnfr rkphfr nal fcryyvat reebef... Vg'f abg zl znwbe.) Fbeel... Ab jr'er abg! Lrf jr ner... naq fb vg pbagvahrf. Nabgure pbyyrtr fghqrag fghpx ba pnzchf qhevat FCEVAT OERNX. Qe. Frhff
jlg@lanl.ARPA (03/20/85)
> >There is a shape other than a circle which would prevent the manhole > >cover from falling through. What is it? > > An equilateral triangle . Not true. The height of an equilateral triangle is less than the length of its side. You could slip the triangle through by dropping it through at one edge of the hole. J. Giles
gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>) (03/22/85)
> Ah, but if you travel at 186,000 mps you WILL make it. Why? > lim t = 0 {limit of t as velocity goes to the speed of light = 0} > v>c > ask a physicist to explain. Yes, please do. This and other similar misunderstandings posted recently make it plain that there is no substitute for a careful study of the subject.
shuju@eros.UUCP (ju Wang Burgess) (03/22/85)
> In article <302@ssc-bee.UUCP> thill@ssc-bee.UUCP (Tom Hill) writes: > > Here is a good interview problem. It can be a bit heartless to give > > to a nervous interviewee but bewarned... a guy I met was actually > > asked this! > > > > You have to travel from town A. to town B. The distance > > between the two towns is 2 miles. If you drive 30 mph for the > > first mile, how fast do you have to drive the second mile in > > order to average 60 mph? > > There are two simple answers. > > a) You cannot travel fast enough. You have already consumed the entire > two minutes required to average 60 mph over the time it takes to make > the trip. > > b) 90 mph. You will then have travelled an average of 60 mph over the > DISTANCE of the trip. > > There probably are other measures possible as well. > -- > > Mike Huybensz ...decvax!genrad!mit-eddie!cybvax0!mrh *** REPLACE THIS LINE WITH YOUR MESSAGE *** I don't believe that the second solution would work as 'mph' stands for Miles Per Hour, so the average 60 miles is measured over time, NOT DISTANCE. I think (a) is the only possible answer. Shu-Ju