Finding the Fourth Proportional to 768,932.72, 1,061,216.72 and 639,642.56

Step by Step Solution

1. Step 1: Write the proportion equation
   768,932.72 : 1,061,216.72 = 639,642.56 : x
2. Step 2: Convert to fraction form
   768,932.72/1,061,216.72 = 639,642.56/x
3. Step 3: Cross multiply
   768,932.72x = 1,061,216.72 × 639,642.56
4. Step 4: Simplify right side
   768,932.72x = 678,799,379,495.60
5. Step 5: Solve for x
   x = 678,799,379,495.60/768,932.72
6. Step 6: Final answer
   x = 882,781.24