VCE Methods Question Thread!

[minhalgill]

For this Q, you use this formula twice and divide by 2 (or use another method)... this formula is very logical, representing the area of a rectangle of height, average value of f(x) in domain, divided by base (domain length).

can you please elaborate on how you would apply this formula to this quesiton?

[sailinginwater]

2014 mav methods exam 1
How would you evaluate this?
(-12+-8root6)/(24)

[MB_]

can you please elaborate on how you would apply this formula to this quesiton?

\(\int_{a}^{b}f(x)dx\) corresponds to the area under the graph which you can just figure out by finding the area of the triangle. Then multiply by \(\frac{1}{b-a}\)

[minhalgill]

for part (a)(i) i solved on my cas and got 1, yet the ans in solutions is 2/27? is it a typo?

[minhalgill]

what is the given and what are we trying to find in this conditional prob?

[MB_]

for part (a)(i) i solved on my cas and got 1, yet the ans in solutions is 2/27? is it a typo?

Yes, they haven't multiplied 2/27 by the 27/2 they put in front of the integral

[sailinginwater]

what is the given and what are we trying to find in this conditional prob?

I think the given is that they spend more than one and a half hours per week

[minhalgill]

I think the given is that they spend more than one and a half hours per week

yet in the solutions they state that is what we are trying to find, not the given. im confused as to why?

[minhalgill]

how do we know that this is binomial?

[VinnyD]

how do we know that this is binomial?

There are numerous trials as one trial is picking a sheep, you do it 4 times. The probabilities stay the same each trial ie 'with replacement'. Depends on the context but usually if there are repeated trials with the same probabilities it tends to be binomial

[minhalgill]

does anyone know how to do this?  i tried doing Pr(X ≥ 2) ≥ 0.9 but when i sub it into my cas, my cas doesnt solve it for some reason?

[undefined]

does anyone know how to do this?  i tried doing Pr(X ≥ 2) ≥ 0.9 but when i sub it into my cas, my cas doesnt solve it for some reason?

What I do is plug random trial numbers into the binomcdf function until the probability reaches just above 0.9.
You can get all the values with a table on the cas too but I'm not sure how to do it.

[VinnyD]

does anyone know how to do this?  i tried doing Pr(X ≥ 2) ≥ 0.9 but when i sub it into my cas, my cas doesnt solve it for some reason?

you essentially do the binomial theorem, having probability of 1-pr(x=0)-pr(x=1). Subbing in the value of n as x, As you know the probabilities you can compute the binomial expansion. You'll end up with a function that you can graph into your calculator and you can set up the line y=0.9 for the intersection and then see which ends you need. The intersection's x value is the n value as that was what we replaced it with

[sailinginwater]

I revised thoroughly for my methods sacs this year but still only ended up with B's for all my sacs. I was wondering is it too much of a stretch to get 40/40 on exam 1 and 65/80 on exam 2 and how to study smart

[Sine]

I revised thoroughly for my methods sacs this year but still only ended up with B's for all my sacs. I was wondering is it too much of a stretch to get 40/40 on exam 1 and 65/80 on exam 2 and how to study smart

Depends on a myriad of factors - some schools have difficult sacs and B's may actually scale up to A's - A+'s. Also you may have underperformed on all those sacs and can do better on the exam. However, the opposite of all these reasons are possible too.

Obviously all those scores are theoretically possible and I don't know about you level of knowledge right now so I have no way in saying the probability of those scores occuring.