Finding the Fourth Proportional to 1,105.89, 1,658.34 and 520.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,105.89 : 1,658.34 = 520.80 : x
2. Step 2: Convert to fraction form
   1,105.89/1,658.34 = 520.80/x
3. Step 3: Cross multiply
   1,105.89x = 1,658.34 × 520.80
4. Step 4: Simplify right side
   1,105.89x = 863,663.47
5. Step 5: Solve for x
   x = 863,663.47/1,105.89
6. Step 6: Final answer
   x = 780.97