Question

A sum of money triples itself in 12 years at simple interest. Find the rate of interest?​

Answer 1

Answer:S.I. equation: principal * interest * term / 100 = amount, so interest = amount * 100/principal * term, so if the principal =1 Rs. then amount = 3 Rs. in 12 years, so the equation becomes, interest = 3 * 100 / 25 * 1 = 12 %

Step-by-step explanation:

Answer 2

Rate of interest = $16\dfrac{2}{3}\%$ p.a.

Simple interest rule:

$I=\dfrac{Ptr}{100}$

where

• I = Interest
• P = Sum of money
• t = Time
• r = Rate of simple interest per annum

Step-by-step explanation:

Let the rate of interest = r% per annum

Sum of money be P

Then sum + interest after 12 years = 3P

So, Interest = 3P - P = 2P

Using simple interest formula, we have

$\quad 2P=\dfrac{P\times 12\times r}{100}$

⇒ 2 × 100 = 12 × r

⇒ r = $\dfrac{200}{12}$

⇒ $r=16\dfrac{2}{3}$

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