An amount of ₹50,000 becomes ₹72,000 in 4 years on a simple rate of interest. The rate of interest is _____ per annum.

The correct option is 11%.

To find the rate of interest per annum, we can use the formula for simple interest.

Step 1: Identify the given values
Principal ($P$) = ₹50,000
Amount ($A$) = ₹72,000
Time ($T$) = 4 years

Step 2: Calculate the Simple Interest ($SI$)
The Simple Interest is the difference between the total amount and the principal amount:

$SI=A-P$

$SI=\mathrm{72,000}-\mathrm{50,000}=\mathrm{22,000}$

So, the total simple interest earned in 4 years is ₹22,000.

Step 3: Use the Simple Interest formula to find the Rate of Interest ($R$)
The formula for Simple Interest is:

$SI=\frac{P\×R\×T}{100}$

Substitute the known values into the formula:

$\mathrm{22,000}=\frac{\mathrm{50,000}\×R\×4}{100}$

Simplify the right side of the equation:

$\mathrm{22,000}=500\×4\×R$

$\mathrm{22,000}=\mathrm{2,000}\×R$

Now, solve for $R$:

$R=\frac{\mathrm{22,000}}{\mathrm{2,000}}$

$R=11$

Thus, the rate of interest is 11% per annum.