Finding the Fourth Proportional to 105,287.43, 145,296.72 and 57,540.78

Step by Step Solution

1. Step 1: Write the proportion equation
   105,287.43 : 145,296.72 = 57,540.78 : x
2. Step 2: Convert to fraction form
   105,287.43/145,296.72 = 57,540.78/x
3. Step 3: Cross multiply
   105,287.43x = 145,296.72 × 57,540.78
4. Step 4: Simplify right side
   105,287.43x = 8,360,486,600.24
5. Step 5: Solve for x
   x = 8,360,486,600.24/105,287.43
6. Step 6: Final answer
   x = 79,406.31