Thread: Combinatorics & Binomial Probability

Hi all, I'm having troubles figuring out how to answer these questions and similar questions.


Combinatorics
In the long run 40% of patients treated for a particular disease with the drug streptomycin are cured. If a doctor were to treat 10 randomly chosen patients with the drug, what is the probability of:
i) 6 cures
ii) more than 8 cures?


A second doctor treats 10 patients with a new treatment and obtains 6 cures. Comment on this result.


And


A management team consists of 12 people. In how many ways could a sub-committee of 4 people be formed?


Thirty-two students are to be interviewed for 8 different jobs. In how many ways could the jobs be filled by selecting from these applicants.

Binomial Probability


A printer which has been giving trouble produces an error message on 3 out of every 10 print jobs on average.



What is the probability of this printer successfully doing 4 print jobs in a row?


Find the probability of drawing 2 red tokens from a box containing 5 red, 3 white and 5 yellow tokens. The tokens are drawn one at a time without replacement?


Thanks a lot.

Originally Posted by Jaytohkay

In the long run 40% of patients treated for a particular disease with the drug streptomycin are cured. If a doctor were to treat 10 randomly chosen patients with the drug, what is the probability of:
i) 6 cures
ii) more than 8 cures?

Apply the fact that

You have p = 0.4 and n=10

find



and

Thanks for the help, but I don't understand those formulas or how to use them, could you please explain a bit more as I'm having trouble interpreting them.

Which bit do you not understand?

Originally Posted by pickslides

Which bit do you not understand?

I've never seen a formula like it before as I rarely deal with them at my level of math. So I don't know how to interpret it correctly.

How I'm seeing the first bit is


You have p = 0.4 and n=10
P(.4) = (10/.4(25)

Then I just don't understand the rest.