Finding the Fourth Proportional to 21,284.91, 31,878.15 and 20,546.80

Step by Step Solution

1. Step 1: Write the proportion equation
   21,284.91 : 31,878.15 = 20,546.80 : x
2. Step 2: Convert to fraction form
   21,284.91/31,878.15 = 20,546.80/x
3. Step 3: Cross multiply
   21,284.91x = 31,878.15 × 20,546.80
4. Step 4: Simplify right side
   21,284.91x = 654,993,892.72
5. Step 5: Solve for x
   x = 654,993,892.72/21,284.91
6. Step 6: Final answer
   x = 30,772.69