Finding the Fourth Proportional to 21,759, 30,017.28 and 12,800.80

Step by Step Solution

1. Step 1: Write the proportion equation
   21,759 : 30,017.28 = 12,800.80 : x
2. Step 2: Convert to fraction form
   21,759/30,017.28 = 12,800.80/x
3. Step 3: Cross multiply
   21,759x = 30,017.28 × 12,800.80
4. Step 4: Simplify right side
   21,759x = 384,245,197.82
5. Step 5: Solve for x
   x = 384,245,197.82/21,759
6. Step 6: Final answer
   x = 17,659.14