Finding the Fourth Proportional to 72,312.08, 99,720.56 and 56,390.72

Step by Step Solution

1. Step 1: Write the proportion equation
   72,312.08 : 99,720.56 = 56,390.72 : x
2. Step 2: Convert to fraction form
   72,312.08/99,720.56 = 56,390.72/x
3. Step 3: Cross multiply
   72,312.08x = 99,720.56 × 56,390.72
4. Step 4: Simplify right side
   72,312.08x = 5,623,314,177.20
5. Step 5: Solve for x
   x = 5,623,314,177.20/72,312.08
6. Step 6: Final answer
   x = 77,764.52