Finding the Fourth Proportional to 99,978.10, 137,956.42 and 64,216.55

Step by Step Solution

1. Step 1: Write the proportion equation
   99,978.10 : 137,956.42 = 64,216.55 : x
2. Step 2: Convert to fraction form
   99,978.10/137,956.42 = 64,216.55/x
3. Step 3: Cross multiply
   99,978.10x = 137,956.42 × 64,216.55
4. Step 4: Simplify right side
   99,978.10x = 8,859,084,630.69
5. Step 5: Solve for x
   x = 8,859,084,630.69/99,978.10
6. Step 6: Final answer
   x = 88,610.25