Finding the Fourth Proportional to 1,128.38, 1,691.50 and 579.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.38 : 1,691.50 = 579.34 : x
2. Step 2: Convert to fraction form
   1,128.38/1,691.50 = 579.34/x
3. Step 3: Cross multiply
   1,128.38x = 1,691.50 × 579.34
4. Step 4: Simplify right side
   1,128.38x = 979,953.61
5. Step 5: Solve for x
   x = 979,953.61/1,128.38
6. Step 6: Final answer
   x = 868.46