Finding the Fourth Proportional to 12,870.09, 17,768.70 and 9,880.20

Step by Step Solution

1. Step 1: Write the proportion equation
   12,870.09 : 17,768.70 = 9,880.20 : x
2. Step 2: Convert to fraction form
   12,870.09/17,768.70 = 9,880.20/x
3. Step 3: Cross multiply
   12,870.09x = 17,768.70 × 9,880.20
4. Step 4: Simplify right side
   12,870.09x = 175,558,309.74
5. Step 5: Solve for x
   x = 175,558,309.74/12,870.09
6. Step 6: Final answer
   x = 13,640.80