Finding the Fourth Proportional to 21,645, 29,870.31 and 12,213.76

Step by Step Solution

1. Step 1: Write the proportion equation
   21,645 : 29,870.31 = 12,213.76 : x
2. Step 2: Convert to fraction form
   21,645/29,870.31 = 12,213.76/x
3. Step 3: Cross multiply
   21,645x = 29,870.31 × 12,213.76
4. Step 4: Simplify right side
   21,645x = 364,828,797.47
5. Step 5: Solve for x
   x = 364,828,797.47/21,645
6. Step 6: Final answer
   x = 16,855.11