Finding the Fourth Proportional to 1,395.45, 1,920.89 and 1,206.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,395.45 : 1,920.89 = 1,206.31 : x
2. Step 2: Convert to fraction form
   1,395.45/1,920.89 = 1,206.31/x
3. Step 3: Cross multiply
   1,395.45x = 1,920.89 × 1,206.31
4. Step 4: Simplify right side
   1,395.45x = 2,317,173.18
5. Step 5: Solve for x
   x = 2,317,173.18/1,395.45
6. Step 6: Final answer
   x = 1,660.52