Finding the Fourth Proportional to 128,986.06, 177,991 and 72,386.50

Step by Step Solution

1. Step 1: Write the proportion equation
   128,986.06 : 177,991 = 72,386.50 : x
2. Step 2: Convert to fraction form
   128,986.06/177,991 = 72,386.50/x
3. Step 3: Cross multiply
   128,986.06x = 177,991 × 72,386.50
4. Step 4: Simplify right side
   128,986.06x = 12,884,145,521.50
5. Step 5: Solve for x
   x = 12,884,145,521.50/128,986.06
6. Step 6: Final answer
   x = 99,887.89