Finding the Fourth Proportional to 12,857.38, 19,268.55 and 7,861.50

Step by Step Solution

1. Step 1: Write the proportion equation
   12,857.38 : 19,268.55 = 7,861.50 : x
2. Step 2: Convert to fraction form
   12,857.38/19,268.55 = 7,861.50/x
3. Step 3: Cross multiply
   12,857.38x = 19,268.55 × 7,861.50
4. Step 4: Simplify right side
   12,857.38x = 151,479,705.83
5. Step 5: Solve for x
   x = 151,479,705.83/12,857.38
6. Step 6: Final answer
   x = 11,781.54