Finding the Fourth Proportional to 1,387.56, 2,080.20 and 693.39

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.56 : 2,080.20 = 693.39 : x
2. Step 2: Convert to fraction form
   1,387.56/2,080.20 = 693.39/x
3. Step 3: Cross multiply
   1,387.56x = 2,080.20 × 693.39
4. Step 4: Simplify right side
   1,387.56x = 1,442,389.88
5. Step 5: Solve for x
   x = 1,442,389.88/1,387.56
6. Step 6: Final answer
   x = 1,039.52