Finding the Fourth Proportional to 21,714.69, 29,955.89 and 12,640.05

Step by Step Solution

1. Step 1: Write the proportion equation
   21,714.69 : 29,955.89 = 12,640.05 : x
2. Step 2: Convert to fraction form
   21,714.69/29,955.89 = 12,640.05/x
3. Step 3: Cross multiply
   21,714.69x = 29,955.89 × 12,640.05
4. Step 4: Simplify right side
   21,714.69x = 378,643,884.19
5. Step 5: Solve for x
   x = 378,643,884.19/21,714.69
6. Step 6: Final answer
   x = 17,437.22