Finding the Fourth Proportional to 1,013.78, 1,398.98 and 571.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,013.78 : 1,398.98 = 571.72 : x
2. Step 2: Convert to fraction form
   1,013.78/1,398.98 = 571.72/x
3. Step 3: Cross multiply
   1,013.78x = 1,398.98 × 571.72
4. Step 4: Simplify right side
   1,013.78x = 799,824.85
5. Step 5: Solve for x
   x = 799,824.85/1,013.78
6. Step 6: Final answer
   x = 788.95