Finding the Fourth Proportional to 1,018.02, 1,404.54 and 639.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,018.02 : 1,404.54 = 639.55 : x
2. Step 2: Convert to fraction form
   1,018.02/1,404.54 = 639.55/x
3. Step 3: Cross multiply
   1,018.02x = 1,404.54 × 639.55
4. Step 4: Simplify right side
   1,018.02x = 898,267.41
5. Step 5: Solve for x
   x = 898,267.41/1,018.02
6. Step 6: Final answer
   x = 882.37