Finding the Fourth Proportional to 2,658.97, 3,988.61 and 810.15

Step by Step Solution

1. Step 1: Write the proportion equation
   2,658.97 : 3,988.61 = 810.15 : x
2. Step 2: Convert to fraction form
   2,658.97/3,988.61 = 810.15/x
3. Step 3: Cross multiply
   2,658.97x = 3,988.61 × 810.15
4. Step 4: Simplify right side
   2,658.97x = 3,231,372.39
5. Step 5: Solve for x
   x = 3,231,372.39/2,658.97
6. Step 6: Final answer
   x = 1,215.27