Help -Rounding up? or down?? (1 Viewer)

[live.fast]

Q8 A) 2001 HSC
an exponential population question...

Question: find the values of N(0) and k and predict the number of koalas that will be present on Kangaroo Island in November 2001

Answer (that me and my book agree on)
koalas = 9511.5154....

Now i've already posted sumfink about a question like diz, cept it was to do with years then, and someone explained to me that if it was say years = 9511.5154... then it would be actually in the 9512nd year, because .5154 represents being 'in' the second year..

but with this question, my book says the number of koalas therefore = 9512
but wif diz, u got like half a koala...

does it still mean you round up??

because wouldn't you have only REALLY 9511 koalas??

(lol i dont like the idea of half a koala...yuccckkkyyyyy!!)

 

[xoxo]

koalas are sooo cute
but back to your question...
hmm
well i guess you cant take it literally and just look at is more as a number than actual koalas...but i get what your saying
hope that helped...probably not but whatever

 

[live.fast]

lol i wanted ta noe which'd be moooree right in the HSC exam? coz da book i got, is not BOS endorsed or nefink ...

so is da book wrong, by BOS standards? or not?

 

[housemouse]

In one of my internal exams, i got a similiar question to that and rounded down due the same reasoning you provided however i was deducted one mark cause you are meant to round up regardless of anything else.

 

[Riviet]

The reason why you round up in these type of questions is because anything below the decimal answer that appears on your calculator will indicate a time period BEFORE the one asked in the question, so strictly speaking, you would be wrong in rounding down. By rounding UP to the nearest integer, we are counting the first whole number of koalas during the specified year in the question. Hope that helps.

 

[drewgcn]

A little disagreement with that, so I checked with someone else.

My understanding is that you would round years up, as they are time periods required to reach the WHOLE number, but you wouldn't round less than a WHOLE number up?

I.e.

Say koalas start at 2, increasing at a rate of 0.1koalas per hour

How many koalas after 2 seconds?
You'd get around 2.00002, which you wouldn't round up to 3, right?

But if you had, how many days until 3 koalas exist?
And it was 10 hours, you'd round up to one day because you can't round down to 0 days...

Yesnomaybehmm?

 

[Riviet]

A little disagreement with that, so I checked with someone else.

My understanding is that you would round years up, as they are time periods required to reach the WHOLE number, but you wouldn't round less than a WHOLE number up?

I.e.

Say koalas start at 2, increasing at a rate of 0.1koalas per hour

How many koalas after 2 seconds?
You'd get around 2.00002, which you wouldn't round up to 3, right?

But if you had, how many days until 3 koalas exist?
And it was 10 hours, you'd round up to one day because you can't round down to 0 days...

Yesnomaybehmm?

Basically, it would be best to apply your common sense to the question, instead of remembering rules for rounding. In reply to your two examples, you would round down to 2 koalas, since this would have occurred around the 1.999 second or so mark and you are correct for your second example.

 

[DoubleX]

You would round up, not only for the reasons everyone else has said, but also because the first number after the decimal place is a 5. 0-4 you round down, 5-9 you round up.

Or am I entirely wrong?

 

[Sober]

You would round up, not only for the reasons everyone else has said, but also because the first number after the decimal place is a 5. 0-4 you round down, 5-9 you round up.

Or am I entirely wrong?

That does not apply here.

 

[DoubleX]

That does not apply here.

I see. Carry on.

 

[Kaley001]

The problem with rounding up is that 1/2 a koala is not 'a koala', which is what the question asked for, so shouldn't, in the case of koalas, you round down?

Although, I think it's safer to round up unless the question specifically asks for something like 'full/complete koalas'...

 

[o.bi.sess]

The problem with rounding up is that 1/2 a koala is not 'a koala', which is what the question asked for, so shouldn't, in the case of koalas, you round down?

Although, I think it's safer to round up unless the question specifically asks for something like 'full/complete koalas'...

I always tend to round up. If you end up getting 0.2 of a koala, you STILL have something of a koala.

The 0.2 is no longer just a meaningless number, because it is counting something. Thus, in the time period, you have a certain number, plus 0.2 of a koala and you can't ignore it. All questions that I've done this in sequences and series have rounded up, despite how small the decimal is.

Lol, I've yet to see a question ask "to the nearest koala".

 

[airie]

I always tend to round up. If you end up getting 0.2 of a koala, you STILL have something of a koala.

*Something*...of a koala...

... Yuck.

 

[~shinigami~]

I always thought the rule of thumb for rounding up was if it was 5 or above then you round up and if it was under 5 then you round down.

e.g. 34.5cm rounds up to 35cm (Nearest cm)
34.4cm rounds down to 34cm (Nearest cm)

 

[Sober]

I always thought the rule of thumb for rounding up was if it was 5 or above then you round up and if it was under 5 then you round down.

e.g. 34.5cm rounds up to 35cm (Nearest cm)
34.4cm rounds down to 34cm (Nearest cm)

That does not apply here, did you not read any of this thread?

An example, how many whole integers are in 7.9? The answer is 7. Often you have to look at the context.