Finding the Fourth Proportional to 21,825, 30,117.08 and 12,870.45

Step by Step Solution

1. Step 1: Write the proportion equation
   21,825 : 30,117.08 = 12,870.45 : x
2. Step 2: Convert to fraction form
   21,825/30,117.08 = 12,870.45/x
3. Step 3: Cross multiply
   21,825x = 30,117.08 × 12,870.45
4. Step 4: Simplify right side
   21,825x = 387,620,404.46
5. Step 5: Solve for x
   x = 387,620,404.46/21,825
6. Step 6: Final answer
   x = 17,760.39