Wannabe an engineer? Test yourself here

2

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  • meanredspider
    meanredspider Posts: 12,337
    If you want to be a Real Engineer (rather than get an Engineering Degree) you don't go to Cambridge University :wink:
    ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH
  • tgotb
    tgotb Posts: 4,714
    meanredspider wrote:
    ...Real Engineer...
    You mean the sort of engineer that wears a blue boiler suit and carries an enormous spanner?

    Edit: Or the sort of engineer that fixes your washing machine?
    Pannier, 120rpm.
  • meanredspider
    meanredspider Posts: 12,337
    TGOTB wrote:
    meanredspider wrote:
    ...Real Engineer...
    You mean the sort of engineer that wears a blue boiler suit and carries an enormous spanner?

    Edit: Or the sort of engineer that fixes your washing machine?

    LMAO, No - the sort of real engineer that does real engineering: like chartered engineers.

    I've forgotten the proportion of Cambridge Engineering graduates that actually go into engineering but I believe it's one of the smallest for any engineering course in the UK.
    ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH
  • Wrath Rob
    Wrath Rob Posts: 2,918
    30%. Shouldn't do a test like this 15 years and a hard training ride after getting my MEng. I'm off to laugh at (more) stupid people on YouTube instead...
    FCN3: Titanium Qoroz.
  • nicklouse
    nicklouse Posts: 50,675
    am an Engineer so cant be arsed doing some stupid quiz.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
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  • Drew123
    Drew123 Posts: 61
    Sketchley wrote:
    "An unbiased cubic die has numbers 1 to 6 inscribed on each side. On average, how many rolls will you need in order to get a 6? "

    If "on each side" it has "numbers 1 to 6 inscribed" that means there is a 6 on each side and also a 1, 2 ,3 ,4 & 5. Therefore you would get a six on every throw. So the answer is one.

    +1, so I got this one "wrong" (along with 4 others...)
  • kieranb
    kieranb Posts: 1,674
    on the dice one, I tried the following approach:

    Prob (not getting a 6 in 1st throw) = (5/6)^1 = 0.8333
    Prob (not getting a 6 in 1st 2 throws) = (5/6)^2 = 0.6944
    Prob (not getting a 6 in 1st 3 throws) = (5/6)^3 = 0.5786
    Prob (not getting a 6 in 1st 4 throws) = (5/6)^4 = 0.4822

    so by the 4th throw the prob of not having got a six is less than half, so in most cases (1-0.4822=0.517 , or approx 52%) you should have got a 6 by the 4th throw.

    Another approach is that as the dice roll is a bernoulli trial (2 possible outcomes, get a 6 or not get a six, with p, prob success = 1/6) then the geometric distribution is used to model the number of trials until the first success, here the formula for the mean of the distirbution = 1/p, so here = 6 but the median of the distribution = -1/log2(1-p), where log2=log base 2, this gives median value to be 3.801. Note also if you add up the probabilities of k=1, k=2, k=3 etc where k=first success at the kth throw then sum of k=1 to 3 = 0.421296 and sum k=1 to 4 = 0.5177, which agrees with the above, this is basically the cumulative distribution function)

    In the link http://www.madandmoonly.com/doctormatt/ ... /dice1.pdf it gives the answer as 6 for the question "On average, how many times must a 6-sided die be rolled until a 6 turns up?"
  • daviesee
    daviesee Posts: 6,386
    I wonder how some people would cope with a complex question.
    This thread would run to pages just for one proof. :lol:
    None of the above should be taken seriously, and certainly not personally.
  • herb71
    herb71 Posts: 253
    90%. Got the Lemonade one wrong. Rushing.
  • stu-bim
    stu-bim Posts: 384
    kieranb wrote:
    In the link http://www.madandmoonly.com/doctormatt/ ... /dice1.pdf it gives the answer as 6 for the question "On average, how many times must a 6-sided die be rolled until a 6 turns up?"

    That's a cruel link. Saved to iBooks and some insomnia reading sorted.
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  • kieranb
    kieranb Posts: 1,674
    how was the weight of oxygen in the room estimated? I just ranomly picked an answer.
  • herb71
    herb71 Posts: 253
    kieranb wrote:
    how was the weight of oxygen in the room estimated? I just ranomly picked an answer.

    Ignore the furniture. This one requires a little bit of prior knowledge. The density of air is approx 1.2kg/m^3.

    Therefore, the mass of the air is 3.5 x 3.5 x 7 x 1.2 = 102.9 KG.
  • kieranb
    kieranb Posts: 1,674
    so why ignore the furniture etc as surely these would reduce the volume of air, especially if those books were really big books? I realise that there wasn't enough info on the contents to use to get an accurate estimate of the volume of air.
  • greg66_tri_v2.0
    greg66_tri_v2.0 Posts: 7,172
    kieranb wrote:
    so why ignore the furniture etc as surely these would reduce the volume of air, especially if those books were really big books? I realise that there wasn't enough info on the contents to use to get an accurate estimate of the volume of air.

    I think it's a guestimating/sense checking test - the room is fairly large, and a way to approach it is to round down the volume (3.5x3.5x7) from 85 to 70cubic metres to take account of the additional material in the room

    For the weight of the air I remembered that a cubic metre of water weighs 1 tonne, and that water is about 800 times denser than air (boring swimming factoid). 70000kgs/800 gets you to a bit less than 100kg. So then you ask yourself "did my guestimating lead to a low or high result? Knocking off 15cubic metres was probably a bit generous (imagine a box 5x3x1m - that a lot of stuff), so round up to get something close enough to plump for an answer.
    Swim. Bike. Run. Yeah. That's what I used to do.

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  • Runtothehills
    Runtothehills Posts: 184
    kieranb wrote:
    so why ignore the furniture etc as surely these would reduce the volume of air, especially if those books were really big books? I realise that there wasn't enough info on the contents to use to get an accurate estimate of the volume of air.

    Look at a typical room and it's pretty obvious that the stuff in it no where near fills all the space, ignoring it for this estimate will be valid-giving the number of metres of A4 files is a red herring to see who wastes their time on it. If you don't believe me hear's the calcs:

    Assuming A4 is 0.2m by 0.3m (overestimate) the files come to 0.42 m3, assuming 200 A4 books 3cm thick that's 0.36 m3, a large 2 drawer filing cabinet will be 1m x 1m x 0.5m (0.5 m3). The Desk and computer are smaller than any of these by far (assume total weight of 100kg, density roughly that of water (wood will be less, metal more so ok -volume 0.1 m3).

    Compare this total of 1.38 m3 to the volume of air in the room - 85 m3. It's small in comparison, the temperature in the room would have more effect on the total weight of air than taking all the stuff out.
  • herb71
    herb71 Posts: 253
    kieranb wrote:
    so why ignore the furniture etc as surely these would reduce the volume of air, especially if those books were really big books? I realise that there wasn't enough info on the contents to use to get an accurate estimate of the volume of air.

    Furniture and books are a red herring and you are not given much information about them. Besides that, the filing cabinet still contains air, as do the files, and the desk is just a few panels, you can't assume they are solid masses.

    They are asking for an 'estimate', as its multiple choice you run a quick calc and choose the closest, in this case 100kg. The next lowest answer is 50kg and a quick sanity check tells you that the furniture, books etc are unlikely to take up half of the available volume.
  • sketchley
    sketchley Posts: 4,238
    daviesee wrote:
    I wonder how some people would cope with a complex question.
    This thread would run to pages just for one proof. :lol:


    Like the Monty hall problem? Although to be fair that is quite simple, just not intuitive.
    --
    Chris

    Genesis Equilibrium - FCN 3/4/5
  • greg66_tri_v2.0
    greg66_tri_v2.0 Posts: 7,172
    Sketchley wrote:
    daviesee wrote:
    I wonder how some people would cope with a complex question.
    This thread would run to pages just for one proof. :lol:


    Like the Monty hall problem? Although to be fair that is quite simple, just not intuitive.

    Were you around when we did that? TWH was particularly perplexed by that, IIRC.
    Swim. Bike. Run. Yeah. That's what I used to do.

    Bike 1
    Bike 2-A
  • sketchley
    sketchley Posts: 4,238
    Greg66 Tri v2.0 wrote:
    Sketchley wrote:
    daviesee wrote:
    I wonder how some people would cope with a complex question.
    This thread would run to pages just for one proof. :lol:


    Like the Monty hall problem? Although to be fair that is quite simple, just not intuitive.

    Were you around when we did that? TWH was particularly perplexed by that, IIRC.

    Yep, IIRC, I think I started it.....

    Edit: viewtopic.php?f=40012&t=12776233&start=120
    --
    Chris

    Genesis Equilibrium - FCN 3/4/5
  • rjsterry
    rjsterry Posts: 29,084
    Sketchley wrote:
    Greg66 Tri v2.0 wrote:
    Sketchley wrote:
    daviesee wrote:
    I wonder how some people would cope with a complex question.
    This thread would run to pages just for one proof. :lol:


    Like the Monty hall problem? Although to be fair that is quite simple, just not intuitive.

    Were you around when we did that? TWH was particularly perplexed by that, IIRC.

    Yep, IIRC, I think I started it.....

    Edit: viewtopic.php?f=40012&t=12776233&start=120

    Well, that was nice to reminisce.

    Here's my favourite maths problem.

    Take two dominoes, and lay one on top of the other so that it overlaps. You can overlap by anything up to half the length of the domino before it tips over. Now try the same with three dominoes. How far past the edge of the bottom domino can you get them to overhang? If you had as many dominoes as you want, could you get past half the length of a domino?
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  • rick_chasey
    rick_chasey Posts: 75,625
    9/10.

    Seems more on the applied maths side than engineering.
    _
  • First.Aspect
    First.Aspect Posts: 16,683
    Greg66 Tri v2.0 wrote:
    TGOTB wrote:
    90%, stupidly overthought the die one and got it wrong.

    Enjoyed the horizon one; didn't realise that calculation was relatively straightforward until I tried it...

    I must admit to still not getting the dice question (which in fact means I think the answer given is wrong, obviously).
    A couple of the questions are ambiguous. That question could be interpreted as asking when you are more likely than not to have thrown a 6, c.f. the birthday question. In the prisoner/hat question does "they will be released" means all three will be released, or just the prisoner in question? Can they hear the others' answers if they wait long enough? This is at least inferred by one of the possible answers, but the correct answer suggests not. Even the setup doesn't specify whether you can use a calculator or not. I didn't, and realised that I could once I got to the question telling me that I couldn't.

    I've had similar job interviews and had to seek clarification because it changes the answer. The difference between a job interview and a university interview is that the latter gives you credit for spotting potential flaws in the question, but if you do so in the former you don't get the job because its just an ars3 kissing contest.

    I got 6/10 without a calculator, listening to the football weekly podcast whilst drinking coffee. I imagine that when you have three cobweb covered academics with wild eyebrows staring at you, its harder.
  • First.Aspect
    First.Aspect Posts: 16,683
    daviesee wrote:
    The dice was the easy one.
    The balloon baffled everyone here. Google has the answer though. :wink:
    Why was the balloon question difficult? I just imaginged what would happen to the golf clubs in the boot of my Jag when I slam the brakes on, and selected the opposite answer.
  • daviesee
    daviesee Posts: 6,386
    First Aspect wrote:
    daviesee wrote:
    The dice was the easy one.
    The balloon baffled everyone here. Google has the answer though. :wink:
    Why was the balloon question difficult? I just imaginged what would happen to the golf clubs in the boot of my Jag when I slam the brakes on, and selected the opposite answer.
    The clubs in your boot go forward when you brake.
    The opposite answer is to go backwards.
    The opposite answer is wrong.
    None of the above should be taken seriously, and certainly not personally.
  • veronese68
    veronese68 Posts: 27,692
    I missed the Monty Hall problem as I wasn't on here then, just had a quick scan of it. Coincidentally this appeared on my Spacetube thingy just now:
    monty_hall.png
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  • kieranb
    kieranb Posts: 1,674
    isn't the balloon one all about inertia, the balloon doesn't move, as initially no force is working on it to change it, but as the truck is moving forward then in relation to the truck the balloon goes backwards.
  • davis
    davis Posts: 2,506
    Greg66 Tri v2.0 wrote:
    Sketchley wrote:
    daviesee wrote:
    I wonder how some people would cope with a complex question.
    This thread would run to pages just for one proof. :lol:


    Like the Monty hall problem? Although to be fair that is quite simple, just not intuitive.

    Were you around when we did that? TWH was particularly perplexed by that, IIRC.

    This
    MontyHallgood.jpg
    was a pretty clear explanation of the Monty Hall problem. It's from The Curious Incident of the Dog in the Night-time
    Sometimes parts break. Sometimes you crash. Sometimes it’s your fault.
  • daviesee
    daviesee Posts: 6,386
    kieranb wrote:
    isn't the balloon one all about inertia, the balloon doesn't move, as initially no force is working on it to change it, but as the truck is moving forward then in relation to the truck the balloon goes backwards.
    Wrong on all counts.
    It is to do with air mass v helium mass and the balloon moves forward in relation to the truck.
    Google the question. It has been asked, answered and explained many times.
    Just for people like us. :wink:
    None of the above should be taken seriously, and certainly not personally.
  • kieranb
    kieranb Posts: 1,674
    ah, but not totally wrong as inertia and mass are basically the same, it's just I didn't take the air into account!
  • daviesee
    daviesee Posts: 6,386
    kieranb wrote:
    ah, but not totally wrong as inertia and mass are basically the same, it's just I didn't take the air into account!
    Which means you got it wrong. Like me. Totally wrong. As in the opposite direction. As in the opposite of right. :wink:
    None of the above should be taken seriously, and certainly not personally.

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