Finding the Fourth Proportional to 28,664.76, 42,989.46 and 7,889.40

Step by Step Solution

1. Step 1: Write the proportion equation
   28,664.76 : 42,989.46 = 7,889.40 : x
2. Step 2: Convert to fraction form
   28,664.76/42,989.46 = 7,889.40/x
3. Step 3: Cross multiply
   28,664.76x = 42,989.46 × 7,889.40
4. Step 4: Simplify right side
   28,664.76x = 339,161,045.72
5. Step 5: Solve for x
   x = 339,161,045.72/28,664.76
6. Step 6: Final answer
   x = 11,831.99