Finding the Fourth Proportional to 20,930.16, 28,870.81 and 12,426.51

Step by Step Solution

1. Step 1: Write the proportion equation
   20,930.16 : 28,870.81 = 12,426.51 : x
2. Step 2: Convert to fraction form
   20,930.16/28,870.81 = 12,426.51/x
3. Step 3: Cross multiply
   20,930.16x = 28,870.81 × 12,426.51
4. Step 4: Simplify right side
   20,930.16x = 358,763,409.17
5. Step 5: Solve for x
   x = 358,763,409.17/20,930.16
6. Step 6: Final answer
   x = 17,140.98