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By definition W is a binomial random variable so it's distribution (PMF) can be represented by: | By definition W is a binomial random variable so it's distribution (PMF) can be represented by: | ||
| − | P(W = m) = (n-k) | + | P(W = m) = ((n-k) over m) where m is the number of questions missed. |
| − | + | ||
P(W = m) = (4/5)^m *(1 - 4/5)^(n-k-m) | P(W = m) = (4/5)^m *(1 - 4/5)^(n-k-m) | ||
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B) C = n - W | B) C = n - W | ||
| − | P(C) = k + (n-k) (1/5)^r * (1 - 1/5)^(n-k-r) | + | P(C) = k + ((n-k) over r) (1/5)^r * (1 - 1/5)^(n-k-r) |
| − | + | ||
Latest revision as of 15:27, 23 September 2008
By definition W is a binomial random variable so it's distribution (PMF) can be represented by:
P(W = m) = ((n-k) over m) where m is the number of questions missed.
P(W = m) = (4/5)^m *(1 - 4/5)^(n-k-m)
B) C = n - W
P(C) = k + ((n-k) over r) (1/5)^r * (1 - 1/5)^(n-k-r)
