Finding the Fourth Proportional to 12,666.78, 17,478.37 and 7,215.99

Step by Step Solution

1. Step 1: Write the proportion equation
   12,666.78 : 17,478.37 = 7,215.99 : x
2. Step 2: Convert to fraction form
   12,666.78/17,478.37 = 7,215.99/x
3. Step 3: Cross multiply
   12,666.78x = 17,478.37 × 7,215.99
4. Step 4: Simplify right side
   12,666.78x = 126,123,771.40
5. Step 5: Solve for x
   x = 126,123,771.40/12,666.78
6. Step 6: Final answer
   x = 9,957.05