Finding the Fourth Proportional to 13,780.50, 20,660.37 and 7,109.85

Step by Step Solution

1. Step 1: Write the proportion equation
   13,780.50 : 20,660.37 = 7,109.85 : x
2. Step 2: Convert to fraction form
   13,780.50/20,660.37 = 7,109.85/x
3. Step 3: Cross multiply
   13,780.50x = 20,660.37 × 7,109.85
4. Step 4: Simplify right side
   13,780.50x = 146,892,131.64
5. Step 5: Solve for x
   x = 146,892,131.64/13,780.50
6. Step 6: Final answer
   x = 10,659.42