Finding the Fourth Proportional to 21,487, 29,644.88 and 12,991.72

Step by Step Solution

1. Step 1: Write the proportion equation
   21,487 : 29,644.88 = 12,991.72 : x
2. Step 2: Convert to fraction form
   21,487/29,644.88 = 12,991.72/x
3. Step 3: Cross multiply
   21,487x = 29,644.88 × 12,991.72
4. Step 4: Simplify right side
   21,487x = 385,137,980.39
5. Step 5: Solve for x
   x = 385,137,980.39/21,487
6. Step 6: Final answer
   x = 17,924.23