Finding the Fourth Proportional to 21,328.25, 31,978.69 and 8,856.89

Step by Step Solution

1. Step 1: Write the proportion equation
   21,328.25 : 31,978.69 = 8,856.89 : x
2. Step 2: Convert to fraction form
   21,328.25/31,978.69 = 8,856.89/x
3. Step 3: Cross multiply
   21,328.25x = 31,978.69 × 8,856.89
4. Step 4: Simplify right side
   21,328.25x = 283,231,557.64
5. Step 5: Solve for x
   x = 283,231,557.64/21,328.25
6. Step 6: Final answer
   x = 13,279.64