This has stumped me.
Assuming a fair coin.
2 flips the P(<=2 H)=1
3 flips the P(<=2 H)=0.875
4 flips the P(<=2 H)=.6875
whats the greatest number of times I can flip a coin and still have P(<=2 H) above 0.2?
Break down the probability distribution for 1 to x flips until 0.2 is obtained?
Assume that the data represents a part of a cumulative distribution and find the differrences between the values above sum to one and solve for the unknowns?