Finding the Fourth Proportional to 1,009.20, 1,520.69 and 830.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,009.20 : 1,520.69 = 830.61 : x
2. Step 2: Convert to fraction form
   1,009.20/1,520.69 = 830.61/x
3. Step 3: Cross multiply
   1,009.20x = 1,520.69 × 830.61
4. Step 4: Simplify right side
   1,009.20x = 1,263,096.17
5. Step 5: Solve for x
   x = 1,263,096.17/1,009.20
6. Step 6: Final answer
   x = 1,251.58