If N=1, certain event and if N=13, impossible event .
The first has a definite month of birth; the probability that the second does not share is 11/12. For further help have please a look at ry1 .
The probability that first is a boy is 12/21. The second has a probability of 11/20 and the third ... .
12/21 · 11/20 · 10/19 = 0,165(41353383458646616541353383459) .
The one that has most at present .
There are 60 numbers not drawn .
The probability of the first hit is 2/15 .
Then the 3rd opens it .
n = ? if P = 1 - (11/12)·(10/12)·...·[(12-n)/12] = 1/2. Have please a look at ry1 .
At each node there are 2 possible ways each with 1/2 probability .
Initially it can travel horizontally or vertically with equal probabilities .
All ways go to Rome, it sholuld move and no other way to go .
sample space:
{{1,1,1},{1,1,2},{1,1,3},{1,1,4},{1,1,5},{1,1,6},
{1,2,1},{1,2,2},{1,2,3},{1,2,4},{1,2,5},{1,2,6},
{1,3,1},{1,3,2},{1,3,3},{1,3,4},{1,3,5},{1,3,6},
{1,4,1},{1,4,2},{1,4,3},{1,4,4},{1,4,5},{1,4,6},
{1,5,1},{1,5,2},{1,5,3},{1,5,4},{1,5,5},{1,5,6},
{1,6,1},{1,6,2},{1,6,3},{1,6,4},{1,265},{1,6,6},...,
and these all repeat 6 times with the same structure giving altogether 6x36 = 216 elements up to {6,6,6}}
We of course need to be careful about {2,.,.},{4,.,.} and {6,.,.} series ... This means we are to get only 3·9 = ... times all odd in the sample space.
1/2·1/2·1/2 = ?
˜ means negation, P(˜E_{1}) is the probability of not happening of E_{1} . For further help, have please a look at ry1.
There are 9 people and 5 of them are at the back row. First chooses one from the ack row with P=5/9.
The probability of spotting a man is 5/9 and ...
Here it is important that you evaluate the sum via 1+4 = 5; 2x5=10; 10+7=17; 2x17=34 and 16+4=20; 2x20=40; 40+26=66; 2x66=132 and ... .
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