Finding the Fourth Proportional to 1,028.72, 1,419.78 and 630.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,028.72 : 1,419.78 = 630.30 : x
2. Step 2: Convert to fraction form
   1,028.72/1,419.78 = 630.30/x
3. Step 3: Cross multiply
   1,028.72x = 1,419.78 × 630.30
4. Step 4: Simplify right side
   1,028.72x = 894,887.33
5. Step 5: Solve for x
   x = 894,887.33/1,028.72
6. Step 6: Final answer
   x = 869.90