Finding the Fourth Proportional to 8,419.90, 12,621.59 and 7,173.31

Step by Step Solution

1. Step 1: Write the proportion equation
   8,419.90 : 12,621.59 = 7,173.31 : x
2. Step 2: Convert to fraction form
   8,419.90/12,621.59 = 7,173.31/x
3. Step 3: Cross multiply
   8,419.90x = 12,621.59 × 7,173.31
4. Step 4: Simplify right side
   8,419.90x = 90,538,564.14
5. Step 5: Solve for x
   x = 90,538,564.14/8,419.90
6. Step 6: Final answer
   x = 10,752.93