9
11
5
7
Formula: Leta,ar,ar2+ar3+...+arnbenterms of a a GP. Then its sum is given by,S=a(1−rn)1−rGiven,An=(34)−(34)2+(34)3−+()n(34)nIt is a Geometric Progression (GP) witha=34,r=and number of terms=nTherefore,An=34×(1−()n)1−()⇒An=34×(1−()n)74⇒An=37[1−()n]Also given,Bn=1−AnTo find: The least odd natural numberp, such thatBn>AnNow,1−An>An⇒1>2×An⇒An<12Substituting the value ofAnin the above equation, we get37×[1−()n]<12⇒1−()n<76⇒1<()n⇒6<()nSincenis odd, then()n=()×34nTherefore,6<()×(34)nMultiplying the entire inequality by, we get16>(34)nNow, Applying log to the base34log3416<34⇒6.228<nTherefore,nshould be7.