Given:
- The money was invested at a simple rate of interest for 3 years.
- If the money was invested at a rate 7% higher, the interest would have been Rs 882 more.

To Find:
- The sum of money invested at the higher rate.

Solution:

Let's assume the original sum of money invested at the lower rate is P.

Step 1: Calculate the interest at the lower rate:
- The interest at the lower rate can be calculated using the formula: I = P * R * T / 100, where I is the interest, P is the principal (sum of money), R is the rate of interest, and T is the time period.
- So, the interest at the lower rate for 3 years is I1 = P * R1 * 3 / 100.

Step 2: Calculate the interest at the higher rate:
- The interest at the higher rate can be calculated using the same formula: I = P * R * T / 100, where I is the interest, P is the principal (sum of money), R is the rate of interest, and T is the time period.
- Since the rate is 7% higher, the new rate is R1 + 7 = R1 + 7/100 * R1 = 107/100 * R1.
- So, the interest at the higher rate for 3 years is I2 = P * (107/100 * R1) * 3 / 100.

Step 3: Calculate the difference in interest:
- According to the given information, the interest at the higher rate is Rs 882 more than the interest at the lower rate. So, I2 - I1 = 882.
- Substituting the values of I1 and I2, we get: P * (107/100 * R1) * 3 / 100 - P * R1 * 3 / 100 = 882.
- Simplifying the equation, we get: P * R1 * 3 * (107/100 - 1) / 100 = 882.

Step 4: Solve for the principal (sum of money):
- Simplifying the equation further, we get: P * R1 * 3 * (7/100) / 100 = 882.
- Cancelling out the common factors, we get: P * R1 * 7 / 10000 = 882.
- Dividing both sides of the equation by R1, we get: P * 7 / 10000 = 882.
- Multiplying both sides of the equation by 10000/7, we get: P = 882 * 10000/7.
- Calculating the value of P, we find: P ≈ 12557.14.

Therefore, the sum of money invested at the higher rate is approximately Rs 12,557.14.