Finding the Fourth Proportional to 85,783.78, 128,533.40 and 60,699.50

Step by Step Solution

1. Step 1: Write the proportion equation
   85,783.78 : 128,533.40 = 60,699.50 : x
2. Step 2: Convert to fraction form
   85,783.78/128,533.40 = 60,699.50/x
3. Step 3: Cross multiply
   85,783.78x = 128,533.40 × 60,699.50
4. Step 4: Simplify right side
   85,783.78x = 7,801,913,113.30
5. Step 5: Solve for x
   x = 7,801,913,113.30/85,783.78
6. Step 6: Final answer
   x = 90,948.58