Finding the Fourth Proportional to 21,002.88, 31,504.92 and 5,420.50

Step by Step Solution

1. Step 1: Write the proportion equation
   21,002.88 : 31,504.92 = 5,420.50 : x
2. Step 2: Convert to fraction form
   21,002.88/31,504.92 = 5,420.50/x
3. Step 3: Cross multiply
   21,002.88x = 31,504.92 × 5,420.50
4. Step 4: Simplify right side
   21,002.88x = 170,772,418.86
5. Step 5: Solve for x
   x = 170,772,418.86/21,002.88
6. Step 6: Final answer
   x = 8,130.90