If three positive real numbers a, b, c are in A.P. such that abc = 4, then the minimum possible value of b is

Let d be the common difference of the A.P., then 4 = abc = (b – d)b (b + d) = b(b2 – d2 )⇒b3=4+bd2≥4 ∵b>0,d2≥0⇒b≥22/3Thus, the minimum possible value of b is 22/3.