Finding the Fourth Proportional to 20,823.30, 28,745.73 and 12,870.18

Step by Step Solution

1. Step 1: Write the proportion equation
   20,823.30 : 28,745.73 = 12,870.18 : x
2. Step 2: Convert to fraction form
   20,823.30/28,745.73 = 12,870.18/x
3. Step 3: Cross multiply
   20,823.30x = 28,745.73 × 12,870.18
4. Step 4: Simplify right side
   20,823.30x = 369,962,719.33
5. Step 5: Solve for x
   x = 369,962,719.33/20,823.30
6. Step 6: Final answer
   x = 17,766.77