Finding the Fourth Proportional to 99,419.91, 137,204.28 and 56,978.55

Step by Step Solution

1. Step 1: Write the proportion equation
   99,419.91 : 137,204.28 = 56,978.55 : x
2. Step 2: Convert to fraction form
   99,419.91/137,204.28 = 56,978.55/x
3. Step 3: Cross multiply
   99,419.91x = 137,204.28 × 56,978.55
4. Step 4: Simplify right side
   99,419.91x = 7,817,700,928.19
5. Step 5: Solve for x
   x = 7,817,700,928.19/99,419.91
6. Step 6: Final answer
   x = 78,633.15