Finding the Fourth Proportional to 99,685.72, 137,561.16 and 56,659.60

Step by Step Solution

1. Step 1: Write the proportion equation
   99,685.72 : 137,561.16 = 56,659.60 : x
2. Step 2: Convert to fraction form
   99,685.72/137,561.16 = 56,659.60/x
3. Step 3: Cross multiply
   99,685.72x = 137,561.16 × 56,659.60
4. Step 4: Simplify right side
   99,685.72x = 7,794,160,301.14
5. Step 5: Solve for x
   x = 7,794,160,301.14/99,685.72
6. Step 6: Final answer
   x = 78,187.33