Finding the Fourth Proportional to 21,820.89, 30,112.86 and 12,868.47

Step by Step Solution

1. Step 1: Write the proportion equation
   21,820.89 : 30,112.86 = 12,868.47 : x
2. Step 2: Convert to fraction form
   21,820.89/30,112.86 = 12,868.47/x
3. Step 3: Cross multiply
   21,820.89x = 30,112.86 × 12,868.47
4. Step 4: Simplify right side
   21,820.89x = 387,506,483.78
5. Step 5: Solve for x
   x = 387,506,483.78/21,820.89
6. Step 6: Final answer
   x = 17,758.51