Question

A sum of money became nine times of itself in 33 years 4 months at simple interest. Find the rate of interest.
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Answer 1

Answer:

24%

Step-by-step explanation:

Answer 2

Answer:

The required rate of interest is 2%

Step-by-step explanation:

Let the principal be P

T be the time i.e. 33yrs 4 months or         ( 1 yr  = 12 months

                                400 months          ∴ 33 yrs = 33 * 12 months

                                                                             = 396 months + 4 months

                                                                             = 400 months )

r be the rate of interest

We know that,

Amount = p + SI

or, 9p = p + $\frac{p * r * t}{100}$

or, 9p = p + $\frac{p*r*400}{100}$

or, 9p - p = p x r x 4

or, 8p = p x r x 4 (now, p gets cancelled from both sides)

or, 8 = 4r

or, 4r = 8

or, r = $\frac{8}{4}$

∴ r = 2 %

So, the required rate of interest is 2 %