Finding the Fourth Proportional to 12,739.50, 17,580.78 and 7,150.50

Step by Step Solution

1. Step 1: Write the proportion equation
   12,739.50 : 17,580.78 = 7,150.50 : x
2. Step 2: Convert to fraction form
   12,739.50/17,580.78 = 7,150.50/x
3. Step 3: Cross multiply
   12,739.50x = 17,580.78 × 7,150.50
4. Step 4: Simplify right side
   12,739.50x = 125,711,367.39
5. Step 5: Solve for x
   x = 125,711,367.39/12,739.50
6. Step 6: Final answer
   x = 9,867.84