A biased coin with probability P,0

Given probability of head =PGiven 25=(1−P)P+(1−P)(1−P)(1−P)P+….=(1−P)P+1+(1−P)2+(1−P)4+…..⇒25=(1−P)P11−(1−P)2 ∵ In G.Pseries, S∞=a1−r⇒25=P−P22P−P2⇒5P−5P2=4P−2P2⇒P=0( or )P=13∴P=13=0.33