Finding the Fourth Proportional to 1,139.52, 1,710.24 and 912.96

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.52 : 1,710.24 = 912.96 : x
2. Step 2: Convert to fraction form
   1,139.52/1,710.24 = 912.96/x
3. Step 3: Cross multiply
   1,139.52x = 1,710.24 × 912.96
4. Step 4: Simplify right side
   1,139.52x = 1,561,380.71
5. Step 5: Solve for x
   x = 1,561,380.71/1,139.52
6. Step 6: Final answer
   x = 1,370.21