Finding the Fourth Proportional to 99,690.38, 137,572.72 and 54,978.38

Step by Step Solution

1. Step 1: Write the proportion equation
   99,690.38 : 137,572.72 = 54,978.38 : x
2. Step 2: Convert to fraction form
   99,690.38/137,572.72 = 54,978.38/x
3. Step 3: Cross multiply
   99,690.38x = 137,572.72 × 54,978.38
4. Step 4: Simplify right side
   99,690.38x = 7,563,524,452.48
5. Step 5: Solve for x
   x = 7,563,524,452.48/99,690.38
6. Step 6: Final answer
   x = 75,870.16