Finding the Fourth Proportional to 9,405.68, 12,978.28 and 5,426.64

Step by Step Solution

1. Step 1: Write the proportion equation
   9,405.68 : 12,978.28 = 5,426.64 : x
2. Step 2: Convert to fraction form
   9,405.68/12,978.28 = 5,426.64/x
3. Step 3: Cross multiply
   9,405.68x = 12,978.28 × 5,426.64
4. Step 4: Simplify right side
   9,405.68x = 70,428,453.38
5. Step 5: Solve for x
   x = 70,428,453.38/9,405.68
6. Step 6: Final answer
   x = 7,487.86