Finding the Fourth Proportional to 2,548.40, 3,820.12 and 815.76

Step by Step Solution

1. Step 1: Write the proportion equation
   2,548.40 : 3,820.12 = 815.76 : x
2. Step 2: Convert to fraction form
   2,548.40/3,820.12 = 815.76/x
3. Step 3: Cross multiply
   2,548.40x = 3,820.12 × 815.76
4. Step 4: Simplify right side
   2,548.40x = 3,116,301.09
5. Step 5: Solve for x
   x = 3,116,301.09/2,548.40
6. Step 6: Final answer
   x = 1,222.85