Finding the Fourth Proportional to 12,890.72, 17,783.16 and 8,917.36

Step by Step Solution

1. Step 1: Write the proportion equation
   12,890.72 : 17,783.16 = 8,917.36 : x
2. Step 2: Convert to fraction form
   12,890.72/17,783.16 = 8,917.36/x
3. Step 3: Cross multiply
   12,890.72x = 17,783.16 × 8,917.36
4. Step 4: Simplify right side
   12,890.72x = 158,578,839.66
5. Step 5: Solve for x
   x = 158,578,839.66/12,890.72
6. Step 6: Final answer
   x = 12,301.78