Finding the Fourth Proportional to 1,128.87, 1,557.90 and 624.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.87 : 1,557.90 = 624.72 : x
2. Step 2: Convert to fraction form
   1,128.87/1,557.90 = 624.72/x
3. Step 3: Cross multiply
   1,128.87x = 1,557.90 × 624.72
4. Step 4: Simplify right side
   1,128.87x = 973,251.29
5. Step 5: Solve for x
   x = 973,251.29/1,128.87
6. Step 6: Final answer
   x = 862.15