Finding the Fourth Proportional to 21,200.50, 29,256.70 and 12,817

Step by Step Solution

1. Step 1: Write the proportion equation
   21,200.50 : 29,256.70 = 12,817 : x
2. Step 2: Convert to fraction form
   21,200.50/29,256.70 = 12,817/x
3. Step 3: Cross multiply
   21,200.50x = 29,256.70 × 12,817
4. Step 4: Simplify right side
   21,200.50x = 374,983,123.90
5. Step 5: Solve for x
   x = 374,983,123.90/21,200.50
6. Step 6: Final answer
   x = 17,687.47