Finding the Fourth Proportional to 12,839.64, 19,260.71 and 3,479.78

Step by Step Solution

1. Step 1: Write the proportion equation
   12,839.64 : 19,260.71 = 3,479.78 : x
2. Step 2: Convert to fraction form
   12,839.64/19,260.71 = 3,479.78/x
3. Step 3: Cross multiply
   12,839.64x = 19,260.71 × 3,479.78
4. Step 4: Simplify right side
   12,839.64x = 67,022,919.74
5. Step 5: Solve for x
   x = 67,022,919.74/12,839.64
6. Step 6: Final answer
   x = 5,220.00