Mathematics - Probability Question with Solution | TestHub

Since total number of subsets of the set $S=2^{20}$ Now, the sum of all number from 1 to $20=\frac{20\times 21}{2}=210$ Then, find the sets which has sum 7 . (1) $\{7\}$ (2) $\{1,6\}$ (3) $\{2,5\}$ (4) $\{3,4\}$ (5) $\{1,2,4\}$ Then, there is only 5 sets which has sum 203 Hence required probability $=\frac{5}{2^{20}}$