Finding the Fourth Proportional to 10,061.20, 15,079.65 and 5,128.30

Step by Step Solution

1. Step 1: Write the proportion equation
   10,061.20 : 15,079.65 = 5,128.30 : x
2. Step 2: Convert to fraction form
   10,061.20/15,079.65 = 5,128.30/x
3. Step 3: Cross multiply
   10,061.20x = 15,079.65 × 5,128.30
4. Step 4: Simplify right side
   10,061.20x = 77,332,969.10
5. Step 5: Solve for x
   x = 77,332,969.10/10,061.20
6. Step 6: Final answer
   x = 7,686.26