Finding the Fourth Proportional to 9,406.40, 12,978.88 and 5,213.76

Step by Step Solution

1. Step 1: Write the proportion equation
   9,406.40 : 12,978.88 = 5,213.76 : x
2. Step 2: Convert to fraction form
   9,406.40/12,978.88 = 5,213.76/x
3. Step 3: Cross multiply
   9,406.40x = 12,978.88 × 5,213.76
4. Step 4: Simplify right side
   9,406.40x = 67,668,765.39
5. Step 5: Solve for x
   x = 67,668,765.39/9,406.40
6. Step 6: Final answer
   x = 7,193.91