Amar borrowed Rs. 10000 from Sachin at simple interest. After 4 years, Sachin received Rs. 5000 more than the amount given to Amar on loan. Find the rate of interest.

The correct option is 12.5%.

Let us break down the problem step-by-step to find the simple interest rate.

Step 1: Identify the given information
Principal amount borrowed ($P$) = Rs. 10000
Time period ($T$) = 4 years
Total amount received by Sachin after 4 years = Principal + Rs. 5000
Since the extra money received over the principal is the interest earned, the Simple Interest ($\mathrm{SI}$) = Rs. 5000.

Step 2: Formula for Simple Interest

$\mathrm{SI}=\frac{P\times R\times T}{100}$

where $R$ is the annual rate of interest in percentage.

Step 3: Substitute the values and calculate the rate of interest ($R$)

$5000=\frac{10000\times R\times 4}{100}$

Simplifying the right side of the equation:

$5000=100\times R\times 4$

$5000=400\times R$

Now, solve for $R$:

$R=\frac{5000}{400}$

$R=\frac{50}{4}=12.5\%$

Therefore, the rate of interest per annum is 12.5%.