Finding the Fourth Proportional to 13,385.72, 18,471.98 and 7,720.48

Step by Step Solution

1. Step 1: Write the proportion equation
   13,385.72 : 18,471.98 = 7,720.48 : x
2. Step 2: Convert to fraction form
   13,385.72/18,471.98 = 7,720.48/x
3. Step 3: Cross multiply
   13,385.72x = 18,471.98 × 7,720.48
4. Step 4: Simplify right side
   13,385.72x = 142,612,490.64
5. Step 5: Solve for x
   x = 142,612,490.64/13,385.72
6. Step 6: Final answer
   x = 10,654.08