Finding the Fourth Proportional to 1,248.89, 1,872.15 and 426.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,248.89 : 1,872.15 = 426.57 : x
2. Step 2: Convert to fraction form
   1,248.89/1,872.15 = 426.57/x
3. Step 3: Cross multiply
   1,248.89x = 1,872.15 × 426.57
4. Step 4: Simplify right side
   1,248.89x = 798,603.03
5. Step 5: Solve for x
   x = 798,603.03/1,248.89
6. Step 6: Final answer
   x = 639.45