At what rate percent on simple interest will a sum of money double itself in 30 years?

One Answer on this Question

1. A=P+SI——(1)
   sum of money after 30 years = Double the money
   A=2P———-(2)

   Equate 1 and 2
   P+SI=2P
   SI=2P-P
   SI=P————-(3)

   WKT, SI= PTR/100

   Equate 3 and SI

   P=PTR/100
   P=P*30*R/100
   R=P*100/P*30
   R=100/30 or 10/3 or 3(1/3) %

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