Finding the Fourth Proportional to 1,011.59, 1,396.05 and 618.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,011.59 : 1,396.05 = 618.50 : x
2. Step 2: Convert to fraction form
   1,011.59/1,396.05 = 618.50/x
3. Step 3: Cross multiply
   1,011.59x = 1,396.05 × 618.50
4. Step 4: Simplify right side
   1,011.59x = 863,456.93
5. Step 5: Solve for x
   x = 863,456.93/1,011.59
6. Step 6: Final answer
   x = 853.56