At what rate percent per annum of simple interest will as sum of money double itself in 12 years?

At what rate percent per annum simple interest will a sum double itself in 10 years?

Answer

Verified

Hint: - Here we go through by the formula of simple interest that we study in the chapter of simple interest. i.e.$SI = \dfrac{{P \times R \times T}}{{100}}$ . By this formula we will be able to calculate the rate.

Complete step-by-step answer:

Here in the question the principal amount is not given.
So let the principle amount be Rs x.
And according to the question at the end the amount become double that means
Amount=2x.
As we know the simple interest means principle amount subtracted from final amount i.e.
S.I= Amount-Principal amount
S.I=2x-x=x
Here the give time T=1o years
Now put these values in the formula of S.I i.e. $SI = \dfrac{{P \times R \times T}}{{100}}$ We get,
$
   \Rightarrow x = \dfrac{{x \times R \times 10}}{{100}} \\
   \Rightarrow R = \dfrac{1}{{10}} \times 100 \\
  \therefore R = 10\% \\
 $
Hence the required rate in which the sum becomes double itself in 10 years is 10%.

Note: - Whenever we face such a type of question, the key concept for solving the question is to first assume the principal amount because the principal amount is not given and then proceed with the question to find the S.I. Then by putting the formula of S.I we will get the terms which we need to find.

Answer

Verified

Hint:- In 8 years money from Interest will be come equal to the principal
amount invested. So, money had been doubled in 8 years.

Let the initial amount of money invested will be Rs. x.
Then after 8 years money had become 2x.
Out of Rs. 2x, money from interest will be 2x – initial amount invested = 2x – x = x.
Let the rate of interest be r.

So, now we will use a simple interest formula.
According to Simple Interest (S.I) formula.
\[ \Rightarrow S.I. = \dfrac{{PRT}}{{100}}\]. Where P is principal amount, R is rate of interest and T will be time period.

So, putting the values in the above formula. We will get,
\[ \Rightarrow x = \dfrac{{xr(8)}}{{100}}\]
On solving the above equation. We will get,
\[ \Rightarrow {\text{ }}r{\text{ }} = {\text{ }}\dfrac{{100}}{8}{\text{ }} = {\text{ }}12.5\]

Hence, the rate of interest to double a money in 8 years will be 12.5% per annum.

Note:- Whenever we came up with this type of problem where we are asked to
find rate of interest then first, we will find the interest on principal amount by
subtracting principal amount from the money after 8 years and then we will
assume rate of interest to be r and then apply, Simple Interest formula and
find the required value of rate of interest.

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

No worries! We‘ve got your back. Try BYJU‘S free classes today!

No worries! We‘ve got your back. Try BYJU‘S free classes today!

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Solution

The correct option is A 5%Given, time = 20 years. Let the sum invested be ₹ 100. So, the Amount received after 20 years = ₹ 200. We know that, Principal + Interest = Amount. Hence, Interest = Amount - Principal = ₹ (200-100) = ₹ 100. The Simple Interest earned on a sum of ₹ P for a period of T years at the rate of R% p.a S.I is given by P×R× T100. So, ₹ 100 = 100× R×20100 Hence, R = 5%.

What rate of simple interest rate per annum will a sum of money double itself in 4 years?

At what rate percent per annum will a sum of money double in 12.5 years?

At what simple interest rate per annum a sum of money will be doubled of itself in 25 years?

At what rate percent per annum simple interest will a sum be double of itself in 8 years?