Finding the Fourth Proportional to 1,011.76, 1,396.20 and 618.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,011.76 : 1,396.20 = 618.72 : x
2. Step 2: Convert to fraction form
   1,011.76/1,396.20 = 618.72/x
3. Step 3: Cross multiply
   1,011.76x = 1,396.20 × 618.72
4. Step 4: Simplify right side
   1,011.76x = 863,856.86
5. Step 5: Solve for x
   x = 863,856.86/1,011.76
6. Step 6: Final answer
   x = 853.82