# One lined question on probability?

1. Feb 28, 2010

### rock.freak667

One lined question on probability??

1. The problem statement, all variables and given/known data
A worker's record shows 60% of his projects are completed on time. If this performance prevails, write the distribution of X=the number of jobs completed in the next 6 jobs. Find the mean and variance of X

2. Relevant equations

3. The attempt at a solution

I think that from x=1-6, P(X=x)= 0.6 ? I mean that was all I was given, there is no reason to think otherwise. Is there? Assuming I am correct, I can easily find the mean and the variance.

2. Feb 28, 2010

### CompuChip

Re: One lined question on probability??

Note that all probabilities should sum to 1...

Does the word "binomial distribution" mean anything to you?

3. Feb 28, 2010

### rock.freak667

Re: One lined question on probability??

ahhhh...I was so caught up in trying to make it uniform distribution

So basically, the distribution is just X~Bin(6,0.6), except I need to write out the numbers and not just the pdf.

4. Feb 28, 2010

### CompuChip

Re: One lined question on probability??

Yes, although it would be nice if you showed why it is binomial. I.e., that it satisfies the properties that a binomial experiment has.

5. Feb 28, 2010

### rock.freak667

Re: One lined question on probability??

The workers 6 projects are independent and the worker can have 0-6 (k) successes (with each success being a constant)

So X~Bin(n,p) = nCkpk(1-p)n-k