Finding the Fourth Proportional to 8,665.60, 13,010.56 and 5,385.10

Step by Step Solution

1. Step 1: Write the proportion equation
   8,665.60 : 13,010.56 = 5,385.10 : x
2. Step 2: Convert to fraction form
   8,665.60/13,010.56 = 5,385.10/x
3. Step 3: Cross multiply
   8,665.60x = 13,010.56 × 5,385.10
4. Step 4: Simplify right side
   8,665.60x = 70,063,166.66
5. Step 5: Solve for x
   x = 70,063,166.66/8,665.60
6. Step 6: Final answer
   x = 8,085.21