If a,1b,c and 1p,q,1rform two arithmetic progression of the same common difference, then a, q, c are in A.P. if
p, b, r are in A.P.
are in A.P.
p, b, r are in G.P.
none of these
Since a, q and c are in A.P., so
2q=a+c
⇒1p+1r=2b
⇒1p,1b,1r are in A.P