With regards to the second part – probably because students don't get taught much at all about the physics or biology etc. behind models, so they usually just see it as an exponential growth maths problem without even thinking about the models themselves or the physical significance of certain constants etc.
reaĺly really quick question :D (2 Viewers)
- Thread starter DepressedPenguino
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DepressedPenguino
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If this question appears in the exam, i would go for 18 years. But i usually round up for this type of question. I am still confused
sorry about that. I just used a random eg that i thought of at the top of my head
nerdasdasd
Dont.msg.me.about.english
I know where this question came from....
nerdasdasd
Dont.msg.me.about.english
ALways round up for exponential questions
You'll have to explain your logic, including why it doesn't apply for other equations.
Well, he didn't actually say it doesn't apply for other equations.
nerdasdasd
Dont.msg.me.about.english
In these questions, they ALWAYS want whole numbers, ..e.g. 1 cat or 2 cat, 3 years, 4 rounds (that is what I was told when I did the HSC).
EVen if it is 8.12 cats or 9.05 dogs..... we always round up to the next number (despite the decimal part being less than 0.5)
(this is the standard for textbook and HSC Qs)
But this time we were talking about years, which is a continuous entity (whereas with dogs or cats etc., those are discrete objects). So why would we need to round years for this Q?
nerdasdasd
Dont.msg.me.about.english
I don't know the answer to that .. I just know the standard.
enigma_1
~~~~ Miss Cricket ~~~~
A rlly quick question and no conclusion after 2 pages lol
Tbh it depends on the question. And since it's a real world model type question it depends on the question. The best thing to do to find your answer is to sub in both the integers on either side of the 18.1 ie 18 and 19 and see which one gives you more than double. The one that gives you less than double kangaroos does not satisfy the question.
But give us the question to be sure
Tbh it depends on the question. And since it's a real world model type question it depends on the question. The best thing to do to find your answer is to sub in both the integers on either side of the 18.1 ie 18 and 19 and see which one gives you more than double. The one that gives you less than double kangaroos does not satisfy the question.
But give us the question to be sure
Isn't it best to just give the exact number (18.1 years or whatever), and if the exact answer is irrational or something, perhaps round that to 2 decimal places or something (after giving the exact answer correct to several decimal places based on the calculator)?
As an extreme example, if it turned out to take ~0.1 years for a population to double, it would be invalid to say 1 year.
(And there's no problem with giving non-integer numbers for years, is there? Since years are essentially continuous (ignoring things like Planck time etc.))
enigma_1
~~~~ Miss Cricket ~~~~
Yeah for something like years you can leave it as 18.1 or if you want to be pedantic you can find what 0.1 of 12 months is and write 18 years and the number of months as the answer. I was suggesting for other questions, they require a definite integer, so we can't give OP a certain answer because there are many different types of questions and each of them require the answer which would make the most common sense.
So OP for a question where you need to find the no. of people, you can't say 18.1 people because that's stupid instead you would round up or down BUT it would depend on the question.
There's no definite rule to round up or down.
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Librah
Not_the_pad
Use some common sense, if a question is asking for some number of dogs, and you get an answer of 20.45, you obviously can't have .45 of a dog. So you round up because it's still some dog. Time is continuous and you can have some fraction of a year, so round appropriately.
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25 years of teaching, and this "standard" has eluded me.
Common sense does say you can't have 0.45 dogs.
But it doesn't explain why you take the next integer.
Not unless it said something like "what is the minimum number of dogs required to be 45% sure that at least two dogs had the same birthday".