Finding the Fourth Proportional to 9,320.74, 12,862.17 and 5,128.90

Step by Step Solution

1. Step 1: Write the proportion equation
   9,320.74 : 12,862.17 = 5,128.90 : x
2. Step 2: Convert to fraction form
   9,320.74/12,862.17 = 5,128.90/x
3. Step 3: Cross multiply
   9,320.74x = 12,862.17 × 5,128.90
4. Step 4: Simplify right side
   9,320.74x = 65,968,783.71
5. Step 5: Solve for x
   x = 65,968,783.71/9,320.74
6. Step 6: Final answer
   x = 7,077.63