Finding the Fourth Proportional to 12,478.80, 17,216.55 and 7,762.78

Step by Step Solution

1. Step 1: Write the proportion equation
   12,478.80 : 17,216.55 = 7,762.78 : x
2. Step 2: Convert to fraction form
   12,478.80/17,216.55 = 7,762.78/x
3. Step 3: Cross multiply
   12,478.80x = 17,216.55 × 7,762.78
4. Step 4: Simplify right side
   12,478.80x = 133,648,290.01
5. Step 5: Solve for x
   x = 133,648,290.01/12,478.80
6. Step 6: Final answer
   x = 10,710.03