Convergence of series using ratio test

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The discussion focuses on proving the convergence of the series summation of sqrt(An)/n, given that summation of An converges with all An > 0. The ratio test is initially applied, but the limit approaches 1, indicating it is inconclusive. Participants suggest exploring alternative convergence tests since the ratio test does not yield useful results in this case. The conversation emphasizes the need for a different approach to establish the convergence of the series. Ultimately, the challenge lies in finding a suitable method to prove the convergence of the modified series.
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Homework Statement


assume summation of series An converges with all An>0. Prove summation of sqrt(An)/n converges

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The Attempt at a Solution


I Tried using the ratio test which says if lim as n goes to infinity of |Bn+1/Bn|<1 then summation of Bn converges. I let Bn be Sqrt(An)/n and we have...

lim as n goes to infinity of |(sqrt(An+1/An)*n/n+1|. limit of n/n+1 goes to one so i need to prove that |sqrt(An+1/An)|<1. But I got stuck because just because An converges does not mean that |(An+1/An)|<1. Can someone help me or suggest on a different convergence test that I should use?
 
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For your series,
\lim_{n \to \infty} \sqrt{\frac{a_{n+1}}{a_n}} = 1

so the Ratio Test is not going to be any help.

What other tests do you know?
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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