Finding the Fourth Proportional to 1,086.72, 1,629.90 and 470.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.72 : 1,629.90 = 470.31 : x
2. Step 2: Convert to fraction form
   1,086.72/1,629.90 = 470.31/x
3. Step 3: Cross multiply
   1,086.72x = 1,629.90 × 470.31
4. Step 4: Simplify right side
   1,086.72x = 766,558.27
5. Step 5: Solve for x
   x = 766,558.27/1,086.72
6. Step 6: Final answer
   x = 705.39