Finding the Fourth Proportional to 12,783.95, 17,640.59 and 9,428.57

Step by Step Solution

1. Step 1: Write the proportion equation
   12,783.95 : 17,640.59 = 9,428.57 : x
2. Step 2: Convert to fraction form
   12,783.95/17,640.59 = 9,428.57/x
3. Step 3: Cross multiply
   12,783.95x = 17,640.59 × 9,428.57
4. Step 4: Simplify right side
   12,783.95x = 166,325,402.31
5. Step 5: Solve for x
   x = 166,325,402.31/12,783.95
6. Step 6: Final answer
   x = 13,010.49