Finding the Fourth Proportional to 9,887.42, 13,644.55 and 5,639.15

Step by Step Solution

1. Step 1: Write the proportion equation
   9,887.42 : 13,644.55 = 5,639.15 : x
2. Step 2: Convert to fraction form
   9,887.42/13,644.55 = 5,639.15/x
3. Step 3: Cross multiply
   9,887.42x = 13,644.55 × 5,639.15
4. Step 4: Simplify right side
   9,887.42x = 76,943,664.13
5. Step 5: Solve for x
   x = 76,943,664.13/9,887.42
6. Step 6: Final answer
   x = 7,781.98