Finding the Fourth Proportional to 12,840.98, 17,722.59 and 7,806.78

Step by Step Solution

1. Step 1: Write the proportion equation
   12,840.98 : 17,722.59 = 7,806.78 : x
2. Step 2: Convert to fraction form
   12,840.98/17,722.59 = 7,806.78/x
3. Step 3: Cross multiply
   12,840.98x = 17,722.59 × 7,806.78
4. Step 4: Simplify right side
   12,840.98x = 138,356,233.51
5. Step 5: Solve for x
   x = 138,356,233.51/12,840.98
6. Step 6: Final answer
   x = 10,774.59