I think it's a trick question.... so i believe that it is 1/2. However i also get another feeling and thus another answer of 0.49. so help me please, please, please.
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there are 2^5 = 32 possible outcomes of which
0 boys: 1/32
1 boy (could be any of the 5 children): 5c1/32 = 5/32
P[at least 2 boys] = 1 - P[≤1 boy] = 1 - 6/32 = 13/16 <--------
0 boys: 1/32
1 boy (could be any of the 5 children): 5c1/32 = 5/32
P[at least 2 boys] = 1 - P[≤1 boy] = 1 - 6/32 = 13/16 <--------
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P[0] = 1/32
P[1] = 5/32
add
P[1] = 5/32
add
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You need to work this sort of problem "backwards". Figure the probability of NOT meeting the condition and subtract that result from 1.00
To have fewer than two boys, at least four of them must be girls. To have four girls, the probability is:
(1/2) * (1/2) * (1/2) * (1/2) = 1/16 or 0.0625
Subtracting the from 1.00 results in a 0.9375 chance of having two or more boys.
To have fewer than two boys, at least four of them must be girls. To have four girls, the probability is:
(1/2) * (1/2) * (1/2) * (1/2) = 1/16 or 0.0625
Subtracting the from 1.00 results in a 0.9375 chance of having two or more boys.
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2/5