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March 29, 2024, 07:31:11 pm

Author Topic: VCE General & Further Maths Question Thread!  (Read 750420 times)  Share 

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Chocolatepistachio

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Re: VCE General & Further Maths Question Thread!
« Reply #2625 on: June 06, 2021, 10:05:21 pm »
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how do you work this out that this is 82%

fun_jirachi

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Re: VCE General & Further Maths Question Thread!
« Reply #2626 on: June 06, 2021, 11:41:01 pm »
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What have you tried? I'm not overly sure what knowledge you have or the tools you have available to solve this question, so can you please provide more context?
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Chocolatepistachio

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Re: VCE General & Further Maths Question Thread!
« Reply #2627 on: June 08, 2021, 09:37:20 pm »
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i did parts a and b which was just the probability that a healthy person will have a CBF reading below 94.4 which was the result given in the excel command and the probability that a person will have a CBF reading above 94.4 which was just 1- the result.
i just don't get part c why its 91%-9%

fun_jirachi

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Re: VCE General & Further Maths Question Thread!
« Reply #2628 on: June 08, 2021, 10:09:22 pm »
+1
Note that for a density function such as this, \(P(x_1 \leq X \leq x_2) = P(X \leq x_2) - P(X \leq x_1)\). You've already calculated \(P(X \leq 94.4)\). Since this is normally distributed, you can conclude that \(P(X \leq 53.6) = P(X \geq 94.4) = 1 - P(X \leq 94.4)\) (how? - that's a question for you to ponder; this will definitely improve your understanding). We then apply the property I mentioned in my first sentence which yields the result given.

If you're still stuck let us know :) 
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ErnieTheBirdi

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Re: VCE General & Further Maths Question Thread!
« Reply #2629 on: June 09, 2021, 12:04:23 pm »
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Someone please let me know, I recently royally screwed up my financial SAC ( I don't even know if I'll pass tbh). I scored a 91 % on the first DATA SAC. So my question is, if I do mess up my financial SAC but get 90+ on all the upcoming network and matrices SAC and then do relatively well in the exam. Does that still mean I am able to reach 45+ or at least in the mid 40 range for further? Or is that it for my goals and dreams in further?

Stormbreaker-X

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Re: VCE General & Further Maths Question Thread!
« Reply #2630 on: June 09, 2021, 01:11:44 pm »
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Someone please let me know, I recently royally screwed up my financial SAC ( I don't even know if I'll pass tbh). I scored a 91 % on the first DATA SAC. So my question is, if I do mess up my financial SAC but get 90+ on all the upcoming network and matrices SAC and then do relatively well in the exam. Does that still mean I am able to reach 45+ or at least in the mid 40 range for further? Or is that it for my goals and dreams in further?
You can still score very highly as long as you ace your future SACs and the exam, which I know you will since you seem so committed. All the best :)

Chocolatepistachio

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Re: VCE General & Further Maths Question Thread!
« Reply #2631 on: August 15, 2021, 09:23:40 pm »
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What’s the difference between bias and confounding in statistics

S_R_K

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Re: VCE General & Further Maths Question Thread!
« Reply #2632 on: August 16, 2021, 09:58:54 am »
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What’s the difference between bias and confounding in statistics

Confounding is not really a statistical concept, but a causal one. In the context of experimental design, confounding variables are those which affect both the DV and IV, and hence "confound" any perceived association between the DV and IV.

When people talk about "bias" they could mean a few different things. Statisticians use it in a very precise way: bias is the difference between the expected value of an estimate of a population parameter (eg. sample mean or variance) and the true value of that population parameter (the population mean or variance). But more generally, people might talk about bias, in relation to data / statistics, by talking about features / flaws in the experimental design which tilted the conclusions in one direction.

Chocolatepistachio

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Re: VCE General & Further Maths Question Thread!
« Reply #2633 on: August 18, 2021, 08:38:28 pm »
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How do you do this question

A 95% confidence interval for the population mean based on a sample 109 observations is 48.26 to 52.39. Which of the following is most likely the 99% confidence interval?
A 48. 60 to 52.05
B 52.39 to 56.85
C 47.59 to 53.06

How do you work this out it’s 47.59 to 53.06

Billuminati

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Re: VCE General & Further Maths Question Thread!
« Reply #2634 on: August 18, 2021, 09:24:15 pm »
+2
How do you do this question

A 95% confidence interval for the population mean based on a sample 109 observations is 48.26 to 52.39. Which of the following is most likely the 99% confidence interval?
A 48. 60 to 52.05
B 52.39 to 56.85
C 47.59 to 53.06

How do you work this out it’s 47.59 to 53.06

50.325 is the mean, given that the degrees of freedom is quite high (108 as n= 109), you can assume a normal distribution.

52.39 - 50.325= 2.065 which represents 1.96 standard deviations (since this is the 95% CI).

Hence 1 standard deviation= 1.05357...

From the normal distribution, 99% CI is 2.58 standard deviations above or below the mean.

Hence upper fence of 99% CI= 50.325 + (2.58 x 1.05357...)= 53.04

And lower fence of 99% CI= 50.325 - (2.58 x 1.05357...)= 47.61

Which is the closest to option C. Note that I used the stats table provided in my uni physical + analytical chem unit so there's some minor rounding differences depending on which version of the table you use.
« Last Edit: August 18, 2021, 09:25:58 pm by Billuminati »
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Chocolatepistachio

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Re: VCE General & Further Maths Question Thread!
« Reply #2635 on: August 19, 2021, 11:18:53 am »
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Thanks

If x is from a normal distribution with mean 5 and standard deviation 2 find
 p( -2.3< x < 8.5) to 4 decimal places . Use r commander to answer this question.

How would you do this question . The answer is 0.9598

Billuminati

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Re: VCE General & Further Maths Question Thread!
« Reply #2636 on: August 19, 2021, 12:47:28 pm »
+1
Thanks

If x is from a normal distribution with mean 5 and standard deviation 2 find
 p( -2.3< x < 8.5) to 4 decimal places . Use r commander to answer this question.

How would you do this question . The answer is 0.9598

You know the normal distribution has this formula:
https://www.thoughtco.com/thmb/8teul80x5qdrwyFNdvv_ATs_mJY=/1250x0/filters:no_upscale():max_bytes(150000):strip_icc()/bellformula-56b749555f9b5829f8380dc8.jpg

Plug in your values for standard deviation and mean, then use a definite integral with terminals of 8.5 on top and -2.3 on bottom to find the area under the normal distribution function
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plato

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Re: VCE General & Further Maths Question Thread!
« Reply #2637 on: August 31, 2021, 12:04:23 pm »
+1
You know the normal distribution has this formula:
https://www.thoughtco.com/thmb/8teul80x5qdrwyFNdvv_ATs_mJY=/1250x0/filters:no_upscale():max_bytes(150000):strip_icc()/bellformula-56b749555f9b5829f8380dc8.jpg

Plug in your values for standard deviation and mean, then use a definite integral with terminals of 8.5 on top and -2.3 on bottom to find the area under the normal distribution function
**** This discussion about Confidence intervals and formula for a normal curve does not belong in this thread !
The only statistics, re Normal distributions ,that Further/General Mathematics students should be cocerned about are the difference between population and sample stats, the sample mean (denoted by x-bar), sample standard deviation (denoted by s),  the standardised score calculation  (denoted by z) and the 68%-95%-99.5% rule.

valjaybj

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Re: VCE General & Further Maths Question Thread!
« Reply #2638 on: September 20, 2021, 01:59:47 pm »
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Hi, is time considered a discrete or continuous variable?

valjaybj

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Re: VCE General & Further Maths Question Thread!
« Reply #2639 on: September 22, 2021, 03:22:16 pm »
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Can someone help me with what a "three-median line" is and how this is different to median smoothing? There was a question about 3-median line in the vcaa 2011 exam but I'm not sure if it's still relevant to the current study design. Thanks