Finding the Fourth Proportional to 99,128.50, 136,779.69 and 56,107.78

Step by Step Solution

1. Step 1: Write the proportion equation
   99,128.50 : 136,779.69 = 56,107.78 : x
2. Step 2: Convert to fraction form
   99,128.50/136,779.69 = 56,107.78/x
3. Step 3: Cross multiply
   99,128.50x = 136,779.69 × 56,107.78
4. Step 4: Simplify right side
   99,128.50x = 7,674,404,754.99
5. Step 5: Solve for x
   x = 7,674,404,754.99/99,128.50
6. Step 6: Final answer
   x = 77,418.75