VCE Methods Question Thread!

[helpmepls112]

It's related rates, so it's not explicitly stated in the course as it used to be. However, as I've seen other people say, you're best off knowing it juuuust in case as it's just an application of the chain rule. There's a good guide on the methods resources page I think. You never know what sus stuff vcaa will pull off.

EDIT: I thought you were talking about 2f... my bad. 2e is definitely still on the course (I think), it's just algebraic manipulation etc with the info they give you.

oh i was a little confused on both parts, and its good to know ill go look at the recourse page now, thanks!

[jiham]

Hi!,
Could anyone help me out with question 4.d in 2016 exam 2 vcaa? I dont undrestand what they did in the solutions,

Thanks!

[VanillaRice]

I still don't get it 
Could someone please also have a look at MC 11, I don't know anything

http://www.vcaa.vic.edu.au/Documents/exams/mathematics/2017/nht/2017MM2-nht-w.pdf

Ahmad_A_1999

8 ) We can find the area under the curve from x = -a to x = a

Essentially, the left hand side (the sloped line) of the function is cancelled out, because if you think about it, the average value in this region is 0!
Recall the average value is the value of y which forms a rectangle from x = -a to x = a, and the area of that rectangle is equivalent to the net signed area of f from x = -a to x = a.
So the average value can be given by y in:

Solving for y gives us the average value of a/2.
You can also set up a hybrid function and use the average value formula (as Syndicate has said)


11) Let X = number of blue marbles. We want:

As per sampling from a small population, we can write

Which should give you option C.

Can someone show me how to do Q3d from the 2012 VCAA Exam 2.

CarrymetoUni

We know
Note the type of distribution for each variable.
As per the question, we have


Similarly, we can write


We now have two probabilities involving the normally distributed variable W, and want to determine the mean and SD. I'll leave the rest to you. Post if you run into any trouble.
HINT: We need to use the standard normal distribution, in particular, using the formula:

You will get two simultaneous equations in a and b which you can then solve.

Hi!,
Could anyone help me out with question 4.d in 2016 exam 2 vcaa? I dont undrestand what they did in the solutions,

Thanks!

jiham

We know x₂>x₁. Note both of these are larger than -k.
If we can show g(x₂)-g(x₁)>0, then we have also shown g(x₂)>g(x₁).
So we write

We must somehow show that this expression is greater than zero.
Consider that if we can show that the individual brackets are all positive numbers, then positive numbers multiplied/divided by each other are still positive!

Bracket 1

We know that

So we can easily see

So the first bracketed term is positive.

Bracket 2

Bracket 3

as per the domain of x₁

Bracket 4

as per the domain of x₂

Hope this helps

[atar.notes.user]

QUESTION: (NHT EXAM 2)

A company supplies schools with whiteboard pens.
The total length of time for which a whiteboard pen can be used for writing before it stops working is called its use-time.
There are two types of whiteboard pens: Grade A and Grade B.
The use-time of Grade A whiteboard pens is normally distributed with a mean of 11 hours and a standard deviation of 15 minutes.
a. Find the probability that a Grade A whiteboard pen will have a use-time that is greater than 10.5 hours, correct to three decimal places.

why is the standard deviation different in the working out?

[VanillaRice]

QUESTION: (NHT EXAM 2)

A company supplies schools with whiteboard pens.
The total length of time for which a whiteboard pen can be used for writing before it stops working is called its use-time.
There are two types of whiteboard pens: Grade A and Grade B.
The use-time of Grade A whiteboard pens is normally distributed with a mean of 11 hours and a standard deviation of 15 minutes.
a. Find the probability that a Grade A whiteboard pen will have a use-time that is greater than 10.5 hours, correct to three decimal places.

why is the standard deviation different in the working out?

The standard deviation used in the calculations is 1/4 hours = 15 mins. They converted to hours since the mean is in hours.

Hope this helps

[chantelle.salisbury]

i would be glad on some help for q 4.a on 2014 Math methods 2! i dont understand the working that vcaa have given.
what technology do i use?

[Bri MT]

i would be glad on some help for q 4.a on 2014 Math methods 2! i dont understand the working that vcaa have given.
what technology do i use?

The height of a plant that is just in the super range occurs when 90% of the area under the normal curve has been covered  (heading from left to right).
You use inverse normal to find what the x-value of this is  (x-values=heights)

[chantelle.salisbury]

The height of a plant that is just in the super range occurs when 90% of the area under the normal curve has been covered  (heading from left to right).
You use inverse normal to find what the x-value of this is  (x-values=heights)

duhh.... i should have known re the 90%.. thankyou for your help

another q.... tis more broad.. but how do you find the range of composite questions!?
and what is the definition of strictly increasing? say if i have a cubic function is it only the stationary points that arent strictly increasing?

[VanillaRice]

duhh.... i should have known re the 90%.. thankyou for your help

another q.... tis more broad.. but how do you find the range of composite questions!?
and what is the definition of strictly increasing? say if i have a cubic function is it only the stationary points that arent strictly increasing?

To find the range of composite functions, you must consider the domain of the composite function. You can also sketch it on your calculator (if it's exam 2).

Intervals on which a function is strictly increasing includes both the interval for which f'(x)>0, as well as the stationary points at either end (if there are any). Compare this with increasing intervals, which do not include the stationary points.

Hope this helps

[Ahmad_A_1999]

Ahmad_A_1999

8 ) We can find the area under the curve from x = -a to x = a

Essentially, the left hand side (the sloped line) of the function is cancelled out, because if you think about it, the average value in this region is 0!
Recall the average value is the value of y which forms a rectangle from x = -a to x = a, and the area of that rectangle is equivalent to the net signed area of f from x = -a to x = a.
So the average value can be given by y in:

Solving for y gives us the average value of a/2.
You can also set up a hybrid function and use the average value formula (as Syndicate has said)


11) Let X = number of blue marbles. We want:

As per sampling from a small population, we can write

Which should give you option C.

THANK YOU SO MUCH, Qs 8 makes sense now

I get question 11 as well, but I'm just confused still with the phrasing of the question, 'without replacement' why can you still use the combinations given that it says that

[VanillaRice]

I get question 11 as well, but I'm just confused still with the phrasing of the question, 'without replacement' why can you still use the combinations given that it says that

"Combinations" refers to the number of combinations of a certain number which can be taken from a population without repetition.
Example: "how many combinations of two fruits can we take from two apples and a banana?" Two combinations - two apples, or an apple and a banana. We can't have a combination of 2 bananas.

Hope this helps

[atar.notes.user]

can i pls get help for the Nht Exams
exam 1:
8cii, 6aii
exam 2:
- section a:
q15-17 (quick way of doing 17 bc my cas isnt showing the true/false method properly)
q19 and 20

thank you

btw for eg; in a 4 mark question, do i get consequential marks if i started off with a mistake but then got the right answer for the mistake? or are consequential marks only for questions in parts (like u get part a wrong, then b, c, d etc)?

[thesplaaashman]

Can someone help me with question 3e 2017 nht exam 2? The wording is really confusing me.

[dolner]

Does anyone have a link to ALL the formulas we need to know? Coz I know there's some not on the formula sheet given by VCAA that are required knowledge.

[atar.notes.user]

do i HAVE to write in this notation?
usually i just write 'normal' 'mean=x' 'sd=y'
is that enough?