Finding the Fourth Proportional to 21,342.81, 29,453.15 and 12,390.69

Step by Step Solution

1. Step 1: Write the proportion equation
   21,342.81 : 29,453.15 = 12,390.69 : x
2. Step 2: Convert to fraction form
   21,342.81/29,453.15 = 12,390.69/x
3. Step 3: Cross multiply
   21,342.81x = 29,453.15 × 12,390.69
4. Step 4: Simplify right side
   21,342.81x = 364,944,851.17
5. Step 5: Solve for x
   x = 364,944,851.17/21,342.81
6. Step 6: Final answer
   x = 17,099.19