least half of the songs you release in 2020 end up on the charts? \begin{aligned} &f(n)=1-\sum_{k=0}^{\frac{n}{2}}\left(\begin{array}{l} n \\ k \end{array}\right)\left(\frac{2}{3}\right)^{k}\left(\frac{1}{3}\right)^{n-k}\\ &f(n)=\left(\begin{array}{l} n \\ \frac{n}{2} \end{array}\right) \frac{2^{\frac{n}{2}}}{3^{n}}\\ &f(n)=\sum_{k=\frac{n}{2}}^{n}\left(\begin{array}{l} n \\ k \end{array}\right) \frac{2^{k}}{3^{n}}\\ &f(n)=\sum_{k=\frac{n}{2}+1}^{n}\left(\begin{array}{l} n \\ k \end{array}\right)\left(\frac{2}{3}\right)^{k}\left(\frac{1}{3}\right)^{n-k}\\ &\text { None of the above } \end{aligned}

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