Finding the Fourth Proportional to 12,678.81, 19,019.31 and 3,318.79

Step by Step Solution

1. Step 1: Write the proportion equation
   12,678.81 : 19,019.31 = 3,318.79 : x
2. Step 2: Convert to fraction form
   12,678.81/19,019.31 = 3,318.79/x
3. Step 3: Cross multiply
   12,678.81x = 19,019.31 × 3,318.79
4. Step 4: Simplify right side
   12,678.81x = 63,121,095.83
5. Step 5: Solve for x
   x = 63,121,095.83/12,678.81
6. Step 6: Final answer
   x = 4,978.47