Finding the Fourth Proportional to 21,980.51, 30,332.47 and 12,905.72

Step by Step Solution

1. Step 1: Write the proportion equation
   21,980.51 : 30,332.47 = 12,905.72 : x
2. Step 2: Convert to fraction form
   21,980.51/30,332.47 = 12,905.72/x
3. Step 3: Cross multiply
   21,980.51x = 30,332.47 × 12,905.72
4. Step 4: Simplify right side
   21,980.51x = 391,462,364.73
5. Step 5: Solve for x
   x = 391,462,364.73/21,980.51
6. Step 6: Final answer
   x = 17,809.52