Question 251079
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{{{b=g=0.5}}}, 

{{{(b+g)^5=b^5+5b^4g+10b^3g^2+10b^2g^3+5bg^4+g^5}}}

The 1st term {{{b^5 = (0.5)^5 = 0.03125}}} is the probability of 5 boys

The 2nd term {{{5b^4g = 5(0.5)^4(0.5) = 0.15625}}} is the probability 
of 4 boys and 1 girl.

The 3rd term {{{10b^3g^2 = 10(0.5)^3(0.5)^2 = 0.3125}}} is the probability 
of 3 boys and 2 girls. 

The 4th term {{{10b^2g^3 = 10(0.5)^2(0.5)^3 = 0.3125}}} is the probability 
of 2 boys and 3 girls.

The 5th term {{{5b^4g = 5(0.5)(0.5)^4 = 0.15625}}} is the probability 
of 1 boy and 4 girls.

The 6th term {{{g^5 = (0.5)^5 = 0.03125}}} is the probability of 5 girls.
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a. exactly 3 boys
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That's the 3rd term {{{10b^3g^2 = 10(0.5)^3(0.5)^2 = 0.3125}}}
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b. exactly 4 boys
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That's the 2nd term {{{5b^4g = 5(0.5)^4(0.5) = 0.15625}}} 
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c. exactly 4 girls
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That's the  5th term {{{5bg^4 = 5(0.5)(0.5)^4 = 0.15625}}}

Edwin</pre>