# Binomial distribution answe check

• Mar 15th 2013, 08:27 AM
djstar
Binomial distribution answe check
Hi, I'm very new to statistics and would like some one to check over the first part of the question i have done as well as some help on the other two parts.

1) could some one please check part a and see if i have the correct answer .

2) For the second part do i have to work out the probability of 6 machines failing then seven and eight etc all the way up to 60 and and the results together, so i will have a page full of calculations?

3) i know i have to calculate Part b first but what exactly does the numbers mean in terms of the machines failing.

Any help would be greatly appreciated.
• Mar 15th 2013, 09:00 AM
Shakarri
Re: Binomial distribution answe check
Your answer to 1) is correct but $3.27 \times 10^{-3}$ is 0.327%

For 2) find the chance that 6 machines will fail, and the chance 5 will fail, same for 4, 3, 2, 1, 0 machines and add up all the chances. That is the chance that 6 or less will fail. Remember that [chance 6 or less fail] + [chance more than 6 will fail] = 1
Use this fact to find the chance that more than 6 will fail.

Discuss your findings they probably just want you to talk about [chance 6 or less fail] + [chance more than 6 will fail] = 1 and how it is faster and still valid.
• Mar 15th 2013, 09:01 AM
HallsofIvy
Re: Binomial distribution answe check
Yes, you answer for (a) is correct.

Quote:

2) For the second part do i have to work out the probability of 6 machines failing then seven and eight etc all the way up to 60 and and the results together, so i will have a page full of calculations?
It will be a lot easier to find the probability that less than 6 machines will fail, then subtract from 1.

I don't see any "part b" in your attachment.
• Mar 15th 2013, 09:01 AM
Plato
Re: Binomial distribution answe check
Quote:

Originally Posted by djstar
Hi, I'm very new to statistics and would like some one to check over the first part of the question i have done as well as some help on the other two parts.

1) could some one please check part a and see if i have the correct answer .

2) For the second part do i have to work out the probability of 6 machines failing then seven and eight etc all the way up to 60 and and the results together, so i will have a page full of calculations?

3) i know i have to calculate Part b first but what exactly does the numbers mean in terms of the machines failing.

It looks correct to me. You can cheek it (60!/((5!)(55!))(.22)^(5)(.78)^(55) - Wolfram|Alpha.
I do not see the rest of the question.
What is the whole statement?
• Mar 15th 2013, 09:20 AM
djstar
Re: Binomial distribution answe check
Thank you all for your kind replies, it makes sense to find the probability that less that 6 machines will fail and take it away from 1 I'll work that out in the next day and get you guys to check it please. Just one thing is how is 3.27 \times 10^{-3} 0.327% ???

ps sorry about the part 'B' bit. part b was the question about 6 or more machines failing.
• Mar 15th 2013, 09:30 AM
Shakarri
Re: Binomial distribution answe check
Quote:

Originally Posted by djstar
Just one thing is how is [tex]3.27 \times 10^{-3}/tex] 0.327% ???.

$3.27 \times 10^{-3}= 0.00327$ this is in decimal form. To convert decimal to percentage multiply by 100.