Finding the Fourth Proportional to 1,128.83, 1,557.90 and 709.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.83 : 1,557.90 = 709.50 : x
2. Step 2: Convert to fraction form
   1,128.83/1,557.90 = 709.50/x
3. Step 3: Cross multiply
   1,128.83x = 1,557.90 × 709.50
4. Step 4: Simplify right side
   1,128.83x = 1,105,330.05
5. Step 5: Solve for x
   x = 1,105,330.05/1,128.83
6. Step 6: Final answer
   x = 979.18