Finding the Fourth Proportional to 9,407.20, 12,980.72 and 5,215.20

Step by Step Solution

1. Step 1: Write the proportion equation
   9,407.20 : 12,980.72 = 5,215.20 : x
2. Step 2: Convert to fraction form
   9,407.20/12,980.72 = 5,215.20/x
3. Step 3: Cross multiply
   9,407.20x = 12,980.72 × 5,215.20
4. Step 4: Simplify right side
   9,407.20x = 67,697,050.94
5. Step 5: Solve for x
   x = 67,697,050.94/9,407.20
6. Step 6: Final answer
   x = 7,196.30