Finding the Fourth Proportional to 21,747.42, 30,009.69 and 12,315.78

Step by Step Solution

1. Step 1: Write the proportion equation
   21,747.42 : 30,009.69 = 12,315.78 : x
2. Step 2: Convert to fraction form
   21,747.42/30,009.69 = 12,315.78/x
3. Step 3: Cross multiply
   21,747.42x = 30,009.69 × 12,315.78
4. Step 4: Simplify right side
   21,747.42x = 369,592,739.91
5. Step 5: Solve for x
   x = 369,592,739.91/21,747.42
6. Step 6: Final answer
   x = 16,994.79