Finding the Fourth Proportional to 7,142.76, 9,858.18 and 3,999.72

Step by Step Solution

1. Step 1: Write the proportion equation
   7,142.76 : 9,858.18 = 3,999.72 : x
2. Step 2: Convert to fraction form
   7,142.76/9,858.18 = 3,999.72/x
3. Step 3: Cross multiply
   7,142.76x = 9,858.18 × 3,999.72
4. Step 4: Simplify right side
   7,142.76x = 39,429,959.71
5. Step 5: Solve for x
   x = 39,429,959.71/7,142.76
6. Step 6: Final answer
   x = 5,520.27