Question

Let the positive numbers a, b, c, d be in A.P. Then abc, abd, acd, acd, bcd are in

• A. A.P
• B. G.P
• C. H.P
• D. none of these

Answer 1

The correct option is C H.P

a, b, c, d are in A.P. reversing the terms, d, c, b, a are in A.P.
$\Rightarrow$ abc, abd, acd, bcd are in H.P. Dividing each terms by abcd, $\frac{1}{abc},\frac{1}{abd},\frac{1}{acd},\frac{1}{bcd}$ are in A.P.