Finding the Fourth Proportional to 1,078.72, 1,618.38 and 429.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.72 : 1,618.38 = 429.50 : x
2. Step 2: Convert to fraction form
   1,078.72/1,618.38 = 429.50/x
3. Step 3: Cross multiply
   1,078.72x = 1,618.38 × 429.50
4. Step 4: Simplify right side
   1,078.72x = 695,098.26
5. Step 5: Solve for x
   x = 695,098.26/1,078.72
6. Step 6: Final answer
   x = 644.37