Finding the Fourth Proportional to 21,218.61, 31,819.25 and 9,211.53

Step by Step Solution

1. Step 1: Write the proportion equation
   21,218.61 : 31,819.25 = 9,211.53 : x
2. Step 2: Convert to fraction form
   21,218.61/31,819.25 = 9,211.53/x
3. Step 3: Cross multiply
   21,218.61x = 31,819.25 × 9,211.53
4. Step 4: Simplify right side
   21,218.61x = 293,103,929.89
5. Step 5: Solve for x
   x = 293,103,929.89/21,218.61
6. Step 6: Final answer
   x = 13,813.53