Finding the Fourth Proportional to 1,109.31, 1,520.90 and 1,089.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,109.31 : 1,520.90 = 1,089.55 : x
2. Step 2: Convert to fraction form
   1,109.31/1,520.90 = 1,089.55/x
3. Step 3: Cross multiply
   1,109.31x = 1,520.90 × 1,089.55
4. Step 4: Simplify right side
   1,109.31x = 1,657,096.60
5. Step 5: Solve for x
   x = 1,657,096.60/1,109.31
6. Step 6: Final answer
   x = 1,493.81