Finding the Fourth Proportional to 13,620.73, 20,420.71 and 7,042.72

Step by Step Solution

1. Step 1: Write the proportion equation
   13,620.73 : 20,420.71 = 7,042.72 : x
2. Step 2: Convert to fraction form
   13,620.73/20,420.71 = 7,042.72/x
3. Step 3: Cross multiply
   13,620.73x = 20,420.71 × 7,042.72
4. Step 4: Simplify right side
   13,620.73x = 143,817,342.73
5. Step 5: Solve for x
   x = 143,817,342.73/13,620.73
6. Step 6: Final answer
   x = 10,558.71