VCE Methods Question Thread!

[kensan]

Ok Bhuth-ni-ke
By CAS i do it like this,
 binomCdf(100,0.1,0,9) got the boundaries round the wrong way, should be 9-100    (number of trials, success probability, lower bound, upper bound)
And I get  0.45129 0.6791
I think it would be fairly time consuming to do it by hand, probably a CAS question imo, hopefully someone can confirm.

[Bhootnike]

the answer is 0.6791 .. :\
i understand what you did - u didnt put any value for 'upper bound' right?

[Jenny_2108]

Find the probability of getting at least nine successes in 100 trials for which the probability of success is p = 0.1.

2 questions:

1.is this a calc question?
2. how do you do it lol

The question said at least 9, so lower bound should be 9, upper bound is 100

I believe its CAS ques. You can do it by hand by using combinations but its too long and takes lots of time

[Jenny_2108]

the answer is 0.6791 .. :\
i understand what you did - u didnt put any value for 'upper bound' right?

yep, the answer should be 0.679126
Put in CAS: binomCdf(100,0.1,9,100) then enter

[pi]

Find the probability of getting at least nine successes in 100 trials for which the probability of success is p = 0.1.

2 questions:

1.is this a calc question?
2. how do you do it lol

1. No, be a man and draw a tree diagram.

(or go Pr(x>=9) = Pr(x=1) + Pr(x=2) + ... + Pr(x=8) where Pr(x=y) = 100Cy * (.1)^y * (.9)^(100-y) )

[Bhootnike]

Find the probability of getting at least nine successes in 100 trials for which the probability of success is p = 0.1.

2 questions:

1.is this a calc question?
2. how do you do it lol

The question said at least 9, so lower bound should be 9, upper bound is 100

I believe its CAS ques. You can do it by hand by using combinations but its too long and takes lots of time

thanks for that, i get it now!!
if i was to do it by hand, i'd have to write nCr out 91 times right..?

Find the probability of getting at least nine successes in 100 trials for which the probability of success is p = 0.1.

2 questions:

1.is this a calc question?
2. how do you do it lol

1. No, be a man and draw a tree diagram.

(or go Pr(x>=9) = Pr(x=1) + Pr(x=2) + ... + Pr(x=8) where Pr(x=y) = 100Cy * (.1)^y * (.9)^(100-y) )

the way you mentioned, thats shorter than writing ncr 91 times, but still, its  8 times! too much writing ;p

[kensan]

Find the probability of getting at least nine successes in 100 trials for which the probability of success is p = 0.1.

2 questions:

1.is this a calc question?
2. how do you do it lol

The question said at least 9, so lower bound should be 9, upper bound is 100

I believe its CAS ques. You can do it by hand by using combinations but its too long and takes lots of time

whops XD yeah got the boundaries wrong haha

[Jenny_2108]

the way you mentioned, thats shorter than writing ncr 91 times, but still, its  8 times! too much writing ;p

haha and imagine we have to calculate by hand 0.1^n and 0.9^(100-n)

Anyway, its for CAS so dw 

[barydos]

hey just want to clarify with this question


the answer says A, but I think it's C, is the book wrong? :S

[tony3272]

hey just want to clarify with this question
(Image removed from quote.)

the answer says A, but I think it's C, is the book wrong? :S

I got A as the answer. It's the integral from x=0 to x=20 of x f(x). Are you sure you plugged that in right?

[BubbleWrapMan]

The answer should be 3 times the expected value.

[tony3272]

The answer should be 3 times the expected value.

^ >__< this. . .

Didn't read the end of the question lol. .

[barydos]

Alright cool thanks, just double checking!

[nangwo]

I was wondering with the process of graphing the derivative of a graph, is the shape something you should just know off by heart? I know graphs like x^4 become x^3 to x^2 and then linear, but what about graphs with a rational power?

[Jenny_2108]

I was wondering with the process of graphing the derivative of a graph, is the shape something you should just know off by heart? I know graphs like x^4 become x^3 to x^2 and then linear, but what about graphs with a rational power?

About graph with a rational power, you find derivative then graph it.
There are some basic shapes with rational power graphs. I just remember it
I doubt they have this kind of question in exam 1