1. ## expected value..formula?

explanations, ...

2. Originally Posted by shirel
exercise:

if the die was rolled sixty times, the expected value for the number of times face 5 shows up would be 10.
calculate the probability that it shows up
a) exactly 10 times
b) 10 +/- 1 times (i.e. between 9 and 11)
c) 10 +/- 2 times
d) 10 +/- 5 times
e) 10 +/- 10 times
which range would guarantee a 90 % certainty? 95 % certainty? 99% certainty?

calculations are necessary. but important is the discussion of the results...
can you give me the formula to calculate a) and the one to calculate b c d e..
and how can i calculate the certainty?

can you help me??
thanks for showing me your calculations, thoughts, ideas, explanations, ...
Did you read the solutions to you earlier question about the binomial distribution?

The probability of $\displaystyle n$ favourable outcomes in $\displaystyle N$ trials where the probability of success in a single trial is $\displaystyle p$ has a binomial distribution $\displaystyle B(N,p)$, so:

$\displaystyle p(n~ success) = b(n;N,p) = \frac{N!}{(N-n)!~n!}~p^n (1-p)^{N-n}$.

Now show us what you have done and we will try to help.

RonL

3. yes i did.

4. me again