Frequencies produced when an organ pipe is closed at one end or opened at both ends

1. A.
   $40,80,120,160$, $\_\_\_\_$
2. B.
   $40,80,160,240$, $\_\_\_\_$
3. C.
   $40,120,200,280$, $\_\_\_\_$
4. D.
   $80,160,240,320$, $\_\_\_\_$

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1. A.
   $150,300,450,600,\ldots\ldots.$.
2. B.
   $300,450,600,750,\ldots\ldots$.
3. C.
   $300,400,500,600,\ldots\ldots$.
4. D.
   $300,600,900,1200,\ldots\ldots$

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