Finding the Fourth Proportional to 21,645.96, 29,870.82 and 12,215.40

Step by Step Solution

1. Step 1: Write the proportion equation
   21,645.96 : 29,870.82 = 12,215.40 : x
2. Step 2: Convert to fraction form
   21,645.96/29,870.82 = 12,215.40/x
3. Step 3: Cross multiply
   21,645.96x = 29,870.82 × 12,215.40
4. Step 4: Simplify right side
   21,645.96x = 364,884,014.63
5. Step 5: Solve for x
   x = 364,884,014.63/21,645.96
6. Step 6: Final answer
   x = 16,856.91