# Math Help - What to study?

1. Originally Posted by CaptainBlack
I have just reviewed his postings and there is something odd about the vast majority of them.

RonL
I pointed out some :
- he starts his messages in the title of the post
- he doesn't use the [quote] tags
- he doesn't use the latex, and it seems like he doesn't intend to
- I agree that there's a strange feeling emanating from some of his posts

What I suppose :

I think too much, that's bad for the good standing of my synapses.

Edit :

Originally Posted by janvdl
In a few of them he ended up with religion, by going way off topic... Or are you thinking of something else?
Hihi, I knew you would notice.

2. Originally Posted by Moo
Hihi, I knew you would notice.
No no, he talks about it in weird ways. Like about what Pascal said about believing or not believing in God. (Check my sig for reference.)

Besides that he was always referring to people too. Pascal, Newton...

He also left lines open between every sentence. And I have never seen anyone go off topic like he does.

3. Originally Posted by janvdl
Well this question was based on the Binomial Distribution. Other topics you might want to read up on:
Negative Binomial Distribution
Geometric Distribution
Hypergeometric Distribution
Poisson Distribution
Exponential Distribution
Greatly appreciate the suggestions, janvdl.

I have two ensuing unrelated queries:

1) In part (c), did you use Normal approximation to the binomial or computation by using a recursive evaluation of binomial probabilities?

2) Consider three children - A,B, & C - standing in a row playing 'catch the ball'. A can only throw the ball to B and B can only throw the ball to C. The probability of B & C dropping the ball are 'p' & 'q', respectively. What is the expected number of times ball will be thrown by A before it is successfully caught by C?

Look forward to a terse response.

Best,
wirefree

4. Originally Posted by Moo

What I suppose :
You do realise that some of the regulars/staff here are what you might describe as rather elderly adults, don't you?

RonL

5. Originally Posted by wirefree
Greatly appreciate the suggestions, janvdl.

I have two ensuing unrelated queries:

1) In part (c), did you use Normal approximation to the binomial or computation by using a recursive evaluation of binomial probabilities?

2) Consider three children - A,B, & C - standing in a row playing 'catch the ball'. A can only throw the ball to B and B can only throw the ball to C. The probability of B & C dropping the ball are 'p' & 'q', respectively. What is the expected number of times ball will be thrown by A before it is successfully caught by C?

Look forward to a terse response.

Best,
wirefree
Let X be the random variable number of throws until B and C catch the ball.

X follows a geometric distribution: Geometric distribution - Wikipedia, the free encyclopedia.

The probability of success in a single throw is (1-p)(1-q).

$E(X) = \frac{1}{(1-p)(1-q)}$.

(Terse enough?)

6. Originally Posted by mr fantastic
Let X be the random variable number of throws until B and C catch the ball.

The probability of success in a single throw is pq.
Did you intend probability of success to be 1-pq?

7. Originally Posted by wirefree
Did you intend probability of success to be 1-pq?
Aha! Careless of me.

Actually the probability of success (B and C both catch the ball) is (1 - p)(1 - q).

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