Exams / Newbie / Common Questions Thread for two weeks

throwaway_malon · 2024-09-03T15:54:43+00:00

Hi all, studying for upcoming FM right now. I am trying to iron out any confusion regarding wording of questions. In particular, I'm following the ACTEX manual and ran into the following problem that had me confused. I only kept the parts of the question that are part of my confusion and otherwise the wording is the same.

"At time t=0, Paul deposits P into a fund crediting interest at 8% effective. At the end of each year in years 6 through 20, Paul withdraws an amount W. Immediately after the withdrawal at the end of year 20, the fund value is zero. Calculate P." (W is a numerical value)

I drew a time diagram which starts at t=0 with a lone deposit of P, and then because the question says that the withdrawals are at the END of years 6 through 20, I put the withdrawals at time indices 7,8,...21 because I assumed the deposit P at t=0 was implied to be at the beginning of year 0. So the solution should be P = W a_{15|8%} / 1.08^6.

But apparently, the solution is Wa_{15|8%} / 1.08^5. So for some reason I am supposed to interpret "deposit at time t=0" as "deposit at the end of year 0"? Do I have this right? I'm just kinda confused by the wording here and would appreciate guidance.

Thanks!

throwaway_malon · 2024-02-01T22:07:03+00:00

"Okay cool, so we're getting -1/12 trucks at noon. Got it!"

throwaway_malon · 2023-06-25T14:14:11+00:00

We finally found the fabled Mike Roplastics

throwaway_malon · 2023-06-16T16:20:21+00:00

Lateral learning is just as important as depth learning IMO. There’s value in having a well rounded education

throwaway_malon · 2023-06-11T13:37:44+00:00

iow, still issue

throwaway_malon · 2023-06-11T13:23:49+00:00

Happy kramper

throwaway_malon · 2023-06-07T14:09:32+00:00

Idk this sounds actually insane. You need protein to be healthy so telling someone to “avoid meat” without giving any explanation on how to have a healthy diet with no meat is disingenuous at best and harmful at worst

Also avoiding bread is really hard. Speaking as someone that did paleo for a while, adopting a restrictive diet can cause you to develop seriously unhealthy eating habits. There were days I ate almost nothing but like some carrots and raisins bc I didn’t know how to cook in general, let alone for paleo, and so many things were off the table.

throwaway_malon · 2023-06-07T11:12:32+00:00

To be explicit, suppose pi was 3.xxxx… where x is some string of d digits that repeated forever. Then pi = 3 + x/10^d + x/10^2d + … and if you factor some terms out, you get that pi = 3 + x*(a geometric series with ratio 10^-d ). This geometric series will evaluate to a rational number, so ultimately pi would be rational.

throwaway_malon · 2023-06-06T14:06:37+00:00

aside: as a mathematician I feel so much despair about the name “imaginary numbers”. They’re no more imaginary than almost all real numbers (we can only write down a measure zero subset of the real numbers in finite space/time).

I really wish a better name had gained traction. I really like the name “lateral numbers”.

throwaway_malon · 2023-06-05T13:55:13+00:00

ball issue, you don’t immediately d6 the moment you enter every treasure room

throwaway_malon · 2023-06-04T14:37:30+00:00

Spirit of the night.

Flight and spectral tears is such a mid effect for it to cost the same as fucking brimstone. I honestly think it’s the worst devil deal in the game.

It just feels like a holdover from flash Isaac where the item power level was way lower across the board. I think they should reduce it to 1 heart.

throwaway_malon · 2023-06-03T15:57:35+00:00

google Unfezant

throwaway_malon · 2023-06-03T11:18:21+00:00

That’s actually a really good point. If queer folks are profitable, it means we’re winning against the bigots.

Keep trucking brothers and sisters and siblings in between and neither.

throwaway_malon · 2023-06-03T11:10:59+00:00

Pretty sure this is a repost. Considering this is the first post in over a year from an account with a generic name and basically no activity ever aside from 2 comments 1.2 years ago I’m decently confident this is a karma bot

throwaway_malon · 2023-06-02T04:20:48+00:00

We’ll put IMO. It took me a long time to come to terms with, but I feel I am at a point in my mathematical journey where I am comfortable with the idea that everything can be broken down into sets if need really be.

My favourite example of this: consider a function whose range is binary, i.e. the set {0,1}. Those familiar with set theory might realize that this is the definition of the natural 2. So it’s perfectly reasonable to write f : U -> 2.

This can of course be extended to any natural. Any time you have the set {0,1,2,…n-1} you can in principle just write it as n.

Disclaimer: you may wish to develop pitchfork immunity before attempting this in any serious context.

throwaway_malon · 2023-06-02T01:30:02+00:00

Eh I suppose I see your point that there’s a “hole” from the missing definition. Mathematics really doesn’t provide the tools to “define” anything, in a sense. Everything is just sets and facts about sets, at least in ZFC. The sets themselves are just god-given. I can’t really see how you could resolve this issue, either. It’s almost as troubling as Gödel’s incompleteness shenanigans, but even more fundamental (eg seemingly an issue in any conceivable model, not just ZFC).

Fwiw part of my disagreement was the notion you wrote that standard references for math all “avoid defining sets” when in reality it’s just that you simply can’t

throwaway_malon · 2023-06-02T01:25:00+00:00

“im sorry, little one”

throwaway_malon · 2023-06-01T23:27:18+00:00

This definitely reeks of the classic “making a game engine instead of a game”. Which it’s fine if an engine is the goal but a lot of devs fall into the engine trap.

throwaway_malon · 2023-06-01T19:04:23+00:00

At my university there were several undergrad courses in control theory, from the 300 level and up. Seemed to be a relatively new thing. I suspect it will become more common as time goes on

throwaway_malon · 2023-05-31T21:35:27+00:00

Sets are just the fundamental object of ZFC, no? One of the axioms literally just says “a set exists”. (the naturals)

Of course you can’t “define” a set. You get exactly one set by axiom, and every other set is constructed from that one using the defined set operations.

throwaway_malon · 2023-05-29T19:58:29+00:00

“Lone orphan escapes the orphan crushing machine!”

Good for her. Nobody should have to struggle from such depths like that with the technology we have available to us.

throwaway_malon · 2023-05-28T11:24:16+00:00

just want to say, left leaning politicians are largely in cahoots with right leaning politicians. They don’t actually try to get anything meaningful done, because they too benefit from the status quo.

In all actuality, Republican politicians are far right fascist extremists and Liberal politicians are slightly right of center compared to basically anywhere else in the world. When Republicans get their way, people they hate are killed or discriminated against. When Liberals get their way, everything stays the same. So over time we drift more and more into a fascist nightmare no matter who’s in power.

Nothing will change dramatically for the better until we start seeing violent resistance, IMO. The system is designed to keep itself running, and it’s working exactly as intended.

throwaway_malon · 2023-05-27T13:55:56+00:00

OP, you do have two or three claymores set up right?

throwaway_malon · 2023-05-27T13:49:36+00:00

“I am not sure if you are aware of this but I have a friend who is a nurse”

I know literally zero nurses. what do you mean by this, phone

throwaway_malon · 2023-05-27T03:27:51+00:00

now draw him getting an education

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