Finding the Fourth Proportional to 21,697.68, 30,118.38 and 21,172.80

Step by Step Solution

1. Step 1: Write the proportion equation
   21,697.68 : 30,118.38 = 21,172.80 : x
2. Step 2: Convert to fraction form
   21,697.68/30,118.38 = 21,172.80/x
3. Step 3: Cross multiply
   21,697.68x = 30,118.38 × 21,172.80
4. Step 4: Simplify right side
   21,697.68x = 637,690,436.06
5. Step 5: Solve for x
   x = 637,690,436.06/21,697.68
6. Step 6: Final answer
   x = 29,389.80