Finding the Fourth Proportional to 1,309.98, 1,807.89 and 720.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,309.98 : 1,807.89 = 720.57 : x
2. Step 2: Convert to fraction form
   1,309.98/1,807.89 = 720.57/x
3. Step 3: Cross multiply
   1,309.98x = 1,807.89 × 720.57
4. Step 4: Simplify right side
   1,309.98x = 1,302,711.30
5. Step 5: Solve for x
   x = 1,302,711.30/1,309.98
6. Step 6: Final answer
   x = 994.45