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Problem 79: Find the distribution function of the total number of heads obtained in four tosses of a balanced coin.

Problem 79: Find the distribution function of the total number of heads obtained in four tosses of a balanced coin.


Solution:


Given that $f(0)=\frac{1}{16},f(1)=\frac{4}{16},f(2)=\frac{6}{16},f(3)=\frac{4}{16},f(4)=\frac{1}{16}$
$F(0) = f(0) = \frac{1}{16}$
$F(1) = f(0)+f(1) = \frac{5}{16}$
$F(2) = f(0)+f(1)+f(2) = \frac{11}{16}$
$F(3) = f(0)+f(1)+f(2)+f(3) = \frac{15}{16}$
$F(4) = f(0)+f(1)+f(2)+f(3)+f(4) = \frac{16}{16}=1$

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