Finding the Fourth Proportional to 12,720.65, 17,555.56 and 7,057.22

Step by Step Solution

1. Step 1: Write the proportion equation
   12,720.65 : 17,555.56 = 7,057.22 : x
2. Step 2: Convert to fraction form
   12,720.65/17,555.56 = 7,057.22/x
3. Step 3: Cross multiply
   12,720.65x = 17,555.56 × 7,057.22
4. Step 4: Simplify right side
   12,720.65x = 123,893,343.72
5. Step 5: Solve for x
   x = 123,893,343.72/12,720.65
6. Step 6: Final answer
   x = 9,739.55