Finding the Fourth Proportional to 20,978.48, 31,487.49 and 7,664.37

Step by Step Solution

1. Step 1: Write the proportion equation
   20,978.48 : 31,487.49 = 7,664.37 : x
2. Step 2: Convert to fraction form
   20,978.48/31,487.49 = 7,664.37/x
3. Step 3: Cross multiply
   20,978.48x = 31,487.49 × 7,664.37
4. Step 4: Simplify right side
   20,978.48x = 241,331,773.73
5. Step 5: Solve for x
   x = 241,331,773.73/20,978.48
6. Step 6: Final answer
   x = 11,503.78