Answer :
By using Binomial Distribution of probability, it is obtained that
Probability that the number of heads is 13 or more = [tex]137980(\frac{1}{2})^{20}[/tex]
What is Binomial Distribution?
Binomial distribution is a discrete type probability distribution whose probability mass function is
P(X = k) = [tex]{n \choose k} p^k(1 - p)^{n-k}[/tex]
p is the probability of success.
Here Binomial distribution of probability is used
P(X [tex]\geq[/tex] 13) = P(X = 13) + P(X = 14) + ........ + P(X = 20)
P(X = 13) = [tex]{20 \choose 13} (\frac{1}{2})^{13}( 1 - \frac{1}{2}})^{20-13}[/tex]
= [tex]{20 \choose 13} (\frac{1}{2})^{13}( \frac{1}{2}})^{7}[/tex]
=[tex]{20 \choose1 3} (\frac{1}{2})^{20}[/tex]
P(X = 14) = [tex]{20 \choose14} (\frac{1}{2})^{20}[/tex]
P(X = 20) = [tex]{20 \choose20} (\frac{1}{2})^{20}[/tex]
Total Probability = [tex]({20 \choose 13} + {20 \choose 14} + .... {20 \choose 20})(\frac{1}{2})^{20}[/tex]
= (77520 + 38760 + 15504 + 4845 + 1140 + 190 + 20 + 1)[tex](\frac{1}{2})^{20}[/tex]
= [tex]137980(\frac{1}{2})^{20}[/tex]
To learn more about Binomial Distribution, refer to the link-
https://brainly.com/question/9325204
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