Finding the Fourth Proportional to 1,085.61, 1,628.50 and 392.28

Step by Step Solution

1. Step 1: Write the proportion equation
   1,085.61 : 1,628.50 = 392.28 : x
2. Step 2: Convert to fraction form
   1,085.61/1,628.50 = 392.28/x
3. Step 3: Cross multiply
   1,085.61x = 1,628.50 × 392.28
4. Step 4: Simplify right side
   1,085.61x = 638,820.52
5. Step 5: Solve for x
   x = 638,820.52/1,085.61
6. Step 6: Final answer
   x = 588.44