Maths Methods 3/4 Help Thread 2011

[paulsterio]

Well interpreting a question is a skill, maths extends beyond being able to plug numbers into equations

[nbhindi]

Well interpreting a question is a skill, maths extends beyond being able to plug numbers into equations

AGREED 

[stephanton]

so i think im doing the question correct, but the multi choice options are confusing me... im using stat list editor...?

The travel time on a particular train route is normally distributed random variable with a mean of 45 mins and a std. deviation of 8 mins. if Z is the random variable of the standard normal distribution, then the probability that a travel time more than 55 minutes is equal to
A –    Pr(Z < 1.25)
B –     1- Pr(Z < 1.25)
C -      Pr(Z > -1.25)
D -      Pr(Z <2)
E –     1- Pr(Z <2)

[luken93]

You don't need to use stats list editor, you've gotta be able to do this by hand for exam 1's.

The Pr(Z) involves the standard normal distribution, where the mean = 0 and the std.dev = 1

Therefore, since a travel time of more than 55 minutes is equal to the mean (45) + 1.25 std.dev, then it is equal to

Pr(X > 55) = Pr(Z > 1.25)
= 1 - Pr(Z < 1.25)
= B

[stephanton]

thanks heaps

[adRo93]

Hey can someone please help explain this to me?


The answer is as follows:


And because 'a' is on the left side of the y-axis, i had the factor as 'x+a', so why is it minus?

(Taken from Heffernan exam 2006)

[nacho]

Hey can someone please help explain this to me?
(Image removed from quote.)

The answer is as follows:
(Image removed from quote.)

And because 'a' is on the left side of the y-axis, i had the factor as 'x+a', so why is it minus?

(Taken from Heffernan exam 2006)

because it is "a"
not "-a"
seems like a little trick

[thushan]

'a' is already negative, so you say x-a, not x+a.

Say a = -3, a factor would be x - a = x - (-3) = x + 3.

[paulsterio]

As a simple guide, you just do (x - "whatever is there")
If it says "-a" put "-a" there and you end up with (x+a)
If it says "a" put "a" there and you end up with (x-a)

Simple way of thinking about it

[adRo93]

Ohh ofc, thanks a heap guys

[nacho]

Question attached.
I can never do related rates questions! :|
Every time i think i've gotten the gist, a new type of question like this comes up and i lose 3 marks.. its so annoying
Would anyone have any advise in regards to tackling this topic, its the only thing stopping me from ace!
I always try and identify the variables, but after doing so in this question, i had no idea what to do next.


dawn of the dead is on tv right now

[paulsterio]

This isn't related reates

You just have to do a difference function h(x) = f(x) - g(x)

and differentiate it...etc. you get the gist

[nacho]

where can i get the itute exam solutions for the 2008 exam?
 i can only find their solutions for vcaa exams, but not their own

[b^3]

where can i get the itute exam solutions for the 2008 exam?
 i can only find their solutions for vcaa exams, but not their own

http://www.itute.com/download-free-vce-maths-resources/free-maths-exams/
Under 2008 there is a heading Free trial mathematics exams (not the VCAA ones)
There is the trial exams for itute, then the solutions underneath them (as long as they are the right ones)

[paulsterio]

What do you guys generally think of iTute exams, I personally think they're too obscure and not really what the VCAA would ask? :S