Finding the Fourth Proportional to 128,978.33, 178,027.27 and 77,991.15

Step by Step Solution

1. Step 1: Write the proportion equation
   128,978.33 : 178,027.27 = 77,991.15 : x
2. Step 2: Convert to fraction form
   128,978.33/178,027.27 = 77,991.15/x
3. Step 3: Cross multiply
   128,978.33x = 178,027.27 × 77,991.15
4. Step 4: Simplify right side
   128,978.33x = 13,884,551,991.28
5. Step 5: Solve for x
   x = 13,884,551,991.28/128,978.33
6. Step 6: Final answer
   x = 107,650.27