Finding the Fourth Proportional to 13,678.38, 20,480.56 and 7,090.72

Step by Step Solution

1. Step 1: Write the proportion equation
   13,678.38 : 20,480.56 = 7,090.72 : x
2. Step 2: Convert to fraction form
   13,678.38/20,480.56 = 7,090.72/x
3. Step 3: Cross multiply
   13,678.38x = 20,480.56 × 7,090.72
4. Step 4: Simplify right side
   13,678.38x = 145,221,847.48
5. Step 5: Solve for x
   x = 145,221,847.48/13,678.38
6. Step 6: Final answer
   x = 10,616.89