Finding the Fourth Proportional to 1,213.94, 1,820.60 and 520.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,213.94 : 1,820.60 = 520.72 : x
2. Step 2: Convert to fraction form
   1,213.94/1,820.60 = 520.72/x
3. Step 3: Cross multiply
   1,213.94x = 1,820.60 × 520.72
4. Step 4: Simplify right side
   1,213.94x = 948,022.83
5. Step 5: Solve for x
   x = 948,022.83/1,213.94
6. Step 6: Final answer
   x = 780.95