Finding the Fourth Proportional to 12,810.79, 19,211.57 and 5,415.83

Step by Step Solution

1. Step 1: Write the proportion equation
   12,810.79 : 19,211.57 = 5,415.83 : x
2. Step 2: Convert to fraction form
   12,810.79/19,211.57 = 5,415.83/x
3. Step 3: Cross multiply
   12,810.79x = 19,211.57 × 5,415.83
4. Step 4: Simplify right side
   12,810.79x = 104,046,566.37
5. Step 5: Solve for x
   x = 104,046,566.37/12,810.79
6. Step 6: Final answer
   x = 8,121.79