Finding the Fourth Proportional to 21,003.36, 28,985.61 and 12,503.55

Step by Step Solution

1. Step 1: Write the proportion equation
   21,003.36 : 28,985.61 = 12,503.55 : x
2. Step 2: Convert to fraction form
   21,003.36/28,985.61 = 12,503.55/x
3. Step 3: Cross multiply
   21,003.36x = 28,985.61 × 12,503.55
4. Step 4: Simplify right side
   21,003.36x = 362,423,023.92
5. Step 5: Solve for x
   x = 362,423,023.92/21,003.36
6. Step 6: Final answer
   x = 17,255.48