Finding the Fourth Proportional to 1,128.15, 1,557.38 and 708.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.15 : 1,557.38 = 708.72 : x
2. Step 2: Convert to fraction form
   1,128.15/1,557.38 = 708.72/x
3. Step 3: Cross multiply
   1,128.15x = 1,557.38 × 708.72
4. Step 4: Simplify right side
   1,128.15x = 1,103,742.29
5. Step 5: Solve for x
   x = 1,103,742.29/1,128.15
6. Step 6: Final answer
   x = 978.36