Finding the Fourth Proportional to 128,986.72, 177,988 and 72,404.32

Step by Step Solution

1. Step 1: Write the proportion equation
   128,986.72 : 177,988 = 72,404.32 : x
2. Step 2: Convert to fraction form
   128,986.72/177,988 = 72,404.32/x
3. Step 3: Cross multiply
   128,986.72x = 177,988 × 72,404.32
4. Step 4: Simplify right side
   128,986.72x = 12,887,100,108.16
5. Step 5: Solve for x
   x = 12,887,100,108.16/128,986.72
6. Step 6: Final answer
   x = 99,910.29