1. ## approximation

If you want to find the binomial probability $P(-3.5 \leq X \leq 4.5)$ with $X \sim \text{Bin}(10,0.5)$ do you just round the endpoints?

2. Originally Posted by shilz222
If you want to find the binomial probability $P(-3.5 \leq X \leq 4.5)$ with $X \sim \text{Bin}(10,0.5)$ do you just round the endpoints?
$P(-3.5 \leq X \leq 4.5) = \sum_{i=-3}^{4} P(X=r)=\sum_{i=0}^{4} P(X=r)$

as for a binomial RV $X$, $P(X<0)=0$

RonL

3. Sorry I meant $P(3.5 \leq X \leq 4.5)$.

4. oh I see, you rounded down.

5. Originally Posted by shilz222
oh I see, you rounded down.
No you sum over those integers included in the interval, we are not rounding (the effect may be the same but rounding is not what we are doing)

RonL