Finding the Fourth Proportional to 10,839.60, 16,271.55 and 8,385.30

Step by Step Solution

1. Step 1: Write the proportion equation
   10,839.60 : 16,271.55 = 8,385.30 : x
2. Step 2: Convert to fraction form
   10,839.60/16,271.55 = 8,385.30/x
3. Step 3: Cross multiply
   10,839.60x = 16,271.55 × 8,385.30
4. Step 4: Simplify right side
   10,839.60x = 136,441,828.22
5. Step 5: Solve for x
   x = 136,441,828.22/10,839.60
6. Step 6: Final answer
   x = 12,587.35