Math, asked by Anonymous, 1 year ago

In what time will compound interest at 15% pa be greater than simple interest at 30% pa for the saame principal

Answers

Answered by kvnmurty
2
CA = P ( 1 + 0.15 )^n   total sum at compound interest
Compound interest CI = CA - P 
SA = P (1 + n 0.30)  total sum at simple interest
Simple interest = SI = P n 0.30
CI = SI when 
P[ (1.15)^n - 1 ] =  P n 0.30  =>  1.15^n =  1 + 0.3 n
                 1.15^9 < 3.7      but  1.15^10 > 4         
        =>  ANSWER nearly 10 years


Anonymous: Thanks. I am more interested to know how to find n=10 without resorting to hit and trial method of substitutig different values for n.
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