Finding the Fourth Proportional to 5,389.31, 8,078.78 and 1,688.96

Step by Step Solution

1. Step 1: Write the proportion equation
   5,389.31 : 8,078.78 = 1,688.96 : x
2. Step 2: Convert to fraction form
   5,389.31/8,078.78 = 1,688.96/x
3. Step 3: Cross multiply
   5,389.31x = 8,078.78 × 1,688.96
4. Step 4: Simplify right side
   5,389.31x = 13,644,760.69
5. Step 5: Solve for x
   x = 13,644,760.69/5,389.31
6. Step 6: Final answer
   x = 2,531.82