Finding the Fourth Proportional to 12,978.66, 17,909.47 and 7,311.60

Step by Step Solution

1. Step 1: Write the proportion equation
   12,978.66 : 17,909.47 = 7,311.60 : x
2. Step 2: Convert to fraction form
   12,978.66/17,909.47 = 7,311.60/x
3. Step 3: Cross multiply
   12,978.66x = 17,909.47 × 7,311.60
4. Step 4: Simplify right side
   12,978.66x = 130,946,880.85
5. Step 5: Solve for x
   x = 130,946,880.85/12,978.66
6. Step 6: Final answer
   x = 10,089.40