Mark the correct alternative in the following:

A coin is tossed n times. The probability of getting at least once is greater than 0.8. Then, the least value of n, is


Given:


P(H)=P(T)=1/2


P(H)= H1Tn-1+H2Tn-2+H3Tn-3+…..+Hn-1T1+Hn


Required probability = p= 1-


P0.8





For n= 2



For n=3



So, n=3

1