Question

A sum of money became five times at simple interest rate of 8 percent per annum at what rate p.c will it become sevenfold? ​

Answer 1

Answer:

12%

Step-by-step explanation:

The rate of interest at which amount become seven fold is 12%  

Step-by-step explanation:

Given as :

A sum of money becomes five times at simple interest rate of 8% per annum

Let The rate at which money become 7 times = R%

Let The principal = p

Amount = A

Interest = I

According to question

For Simple Interest

S.I =  

∵   Interest = Amount - principal

Or,   I = 5 P - P

∴      I = 4 P

So,

S.I  × 100 =  p × 8 × t

Or,  4 p  × 100 =  p × 8 × t

Or,   t = 50 years

time period = t = 50 years

Again

For seven times the principal

∵   Interest = Amount - principal

Or,   I = 7 P - P

∴      I = 6 P

So,

S.I  × 100 =  p × 8 × t

Or,  6 p  × 100 =  p × R × 50

Or  R =  12

So, The Rate of interest  = R = 12 %

Hence, The rate of interest at which amount become seven fold is 12%  Answer

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