Finding the Fourth Proportional to 10,685.90, 16,026.42 and 5,135.78

Step by Step Solution

1. Step 1: Write the proportion equation
   10,685.90 : 16,026.42 = 5,135.78 : x
2. Step 2: Convert to fraction form
   10,685.90/16,026.42 = 5,135.78/x
3. Step 3: Cross multiply
   10,685.90x = 16,026.42 × 5,135.78
4. Step 4: Simplify right side
   10,685.90x = 82,308,167.31
5. Step 5: Solve for x
   x = 82,308,167.31/10,685.90
6. Step 6: Final answer
   x = 7,702.50