Finding the Fourth Proportional to 28,456.86, 42,685.77 and 9,989.34

Step by Step Solution

1. Step 1: Write the proportion equation
   28,456.86 : 42,685.77 = 9,989.34 : x
2. Step 2: Convert to fraction form
   28,456.86/42,685.77 = 9,989.34/x
3. Step 3: Cross multiply
   28,456.86x = 42,685.77 × 9,989.34
4. Step 4: Simplify right side
   28,456.86x = 426,402,669.69
5. Step 5: Solve for x
   x = 426,402,669.69/28,456.86
6. Step 6: Final answer
   x = 14,984.18