About 55% of emergency room visits are unnecessary. Assuming each emergency room visit is independent. (Hints: first define the random variable X. Then write the objective of each question in terms of X.)
a) Suppose the distribution of unnecessary emergency room visits can be approximated by a normal distribution. What is the probability that AT LEAST two of them need to be in the emergency room? sample size 15 patients @kropot72 ...

Question

About 55% of emergency room visits are unnecessary. Assuming each emergency room visit is independent. (Hints: first define the random variable X. Then write the objective of each question in terms of X.)
a)	Suppose the distribution of unnecessary emergency room visits can be approximated by a normal distribution. What is the probability that AT LEAST two of them need to be in the emergency room? sample size 15 patients @kropot72 ...

anonymous · Answer

dont know if u can help me @kropot72

kropot72 · Answer

The binomial distribution applies to this question.
Let the number of necessary visits be X.
$$P(X=0)=\left(\begin{matrix}15 \ 0\end{matrix}\right)0.45^{0}0.55^{15}=0.000127$$
$$P(X=1)=\left(\begin{matrix}15 \ 1\end{matrix}\right)0.45^{1}0.55^{14}=0.001565$$
Therefore we can find the required probability as follows:
$$P(X \ \ge2)=1.000000-[P(X=0)+P(X=1)]$$

anonymous · Answer

exactly wat i thought..thanks

kropot72 · Answer

You're welcome :)