VCE Methods Question Thread!

[Frozone]

Sorry the keyboard on my phone and these forums do not work well together. If you don't mind waiting a few hours I will redo it.

No problemo! Thanks in advanced

[Stevensmay]

So we start with
We find
At x=0 the gradient will be 1 so so b = 1

At (1,2) the gradient will be 0 so
We sub in our b value and so find a=-1/2.

Next sub our a and b into the original equation, as well as the co ordinates given. Solve for c.
C=1/2

[BasicAcid]

Hint: m = tan(theta).

So if the slope is at an angle of 45 degrees at x=0, the gradient is tan(45).
In other words, the gradient is 1 (tan45 = 1) at x=0.

You know the drill.

[Stevensmay]

So if the slope is at an angle of 45 degrees at x=0, the gradient is tan(45).
In other words, the gradient is 1 (tan45 = 1) at x=0.

Thanks for catching my typo.
Your last exam is physics as well?

[Frozone]

Hint: m = tan(theta).

So if the slope is at an angle of 45 degrees at x=0, the gradient is tan(45).
In other words, the gradient is 1 (tan45 = 1) at x=0.

You know the drill.

Yeah thanks. I was already aware that 45 degrees was 1. I similar question relating to that was on my previous sac.

[Stevensmay]

Sorry Frozone, I have a feeling that post was directed at me. Was meant to be listening to the teacher and wrote down the gradient as 1/2 by mistake.

[Sanguinne]

An unbiased 8 sided die is rolled 12 times. The probability of obtaining three results greater than 5 is?

[lzxnl]

Pr(one result greater than 5) = 3/8 as you can get 6, 7, 8
So Pr(3 results out of 12) = 12C3*(3/8)^3*(5/8)^9
etc

It's just a binomial question

[Sanguinne]

The probability of Sam beating Abby in a game of cards is 0.36. Abby and Sam decide to play a game everday for n days. What is the fewest number of games they need to play to ensure the probability of Sam winning at least once is greater than 0.85.

[BasicAcid]

The probability of Sam beating Abby in a game of cards is 0.36. Abby and Sam decide to play a game everday for n days. What is the fewest number of games they need to play to ensure the probability of Sam winning at least once is greater than 0.85.

Is the answer 5?

[darklight]

The probability of Sam beating Abby in a game of cards is 0.36. Abby and Sam decide to play a game everday for n days. What is the fewest number of games they need to play to ensure the probability of Sam winning at least once is greater than 0.85.

Is the answer 5?

I got 5 too.
This is how I did it.

Pr(success; eg Sam beating Abby) = 0.36
Pr(X greater than or equal to 1) > 0.85
1 - Pr(X less than 1) > 0.85
- Pr (X less than 1) > -.015
Pr (X less than 1) < 0.15 (flipping because of "negative")

Another way of writing Pr (X less than 1) is Pr (X=0).
Pr (X=0) < 0.15
using binomial theorem, we get nC0 * (0.36)^0 * (0.64)^n <0.15
(0.64)^n < 0.15

However, you calculator cannot help the above. Type (0.64)^n = 0.15, to get n = 4.2509

However, you can't have 4.2509 days since they are playing once a day. You can't round down, because this would not ensure the probability to be greater than 0.85. Therefore you round up, getting n = 5

[fleet street]

Also, for these types of questions in general, since most of the time they are multiple choice, you can just type in on your calculator 1-binomialPDf(0,a,0.36), replace "a" with each of the multiple choice values, and see which one is the lowest that brings you above 0.85. However, it's still worth knowing darklight's way, because it might not always be multiple choice.

[clıppy]

Also, for these types of questions in general, since most of the time they are multiple choice, you can just type in on your calculator 1-binomialPDf(0,a,0.36), replace "a" with each of the multiple choice values, and see which one is the lowest that brings you above 0.85. However, it's still worth knowing darklight's way, because it might not always be multiple choice.

I didn't know you could do that for the MC ones. Thanks for the tip

[nspire]

Hi everyone!

Can someone kindly help me with understanding of random variables?

My question is:

Is the time it takes to shutdown a computer, measured in seconds, a discrete or continuous random variable?

Thank you 

[Jaswinder]

Hi everyone!

Can someone kindly help me with understanding of random variables?

My question is:

Is the time it takes to shutdown a computer, measured in seconds, a discrete or continuous random variable?

Thank you 

Any measurement related to time, is usually continuous as you can never get an exact amount. Examples of discrete variables are number of cans, number of people etcc