Finding the Fourth Proportional to 1,018.89, 1,405.89 and 620.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,018.89 : 1,405.89 = 620.42 : x
2. Step 2: Convert to fraction form
   1,018.89/1,405.89 = 620.42/x
3. Step 3: Cross multiply
   1,018.89x = 1,405.89 × 620.42
4. Step 4: Simplify right side
   1,018.89x = 872,235.24
5. Step 5: Solve for x
   x = 872,235.24/1,018.89
6. Step 6: Final answer
   x = 856.06