Question

bout 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.If you randomly select 15 patients from those visiting the emergency department, what is the chance that all of them need to be in the emergency room?

b.What is the expected number from the 15 randomly selected patients, who don’t need to be in the emergency room and what is the standard deviation of that number. @dumbcow @terenzreignz

Answer 1

Can we use a binomial approximation?

Answer 2

yes we can @tkhunny

Answer 3

part 1)
45% chance visit is necessary ....chance all 15 is (.45)^15

part 2)
probability is .55 , sample = 15
mean = .55*15
std dev = sqrt(.55*15*.45)

Answer 4

so i only need to find .45^15. and that would be mine answer ryt?

Answer 5

yes

here is a reference
http://en.wikipedia.org/wiki/Binomial_distribution#Mean_and_variance

Answer 6

aww..thanks soo much

Answer 7

yw

Answer 8

one last question @dumbcow

Answer 9

if im ask to find the probability that at least two of them need to be in the emergency room.how do i go about it?