Finding the Fourth Proportional to 2,160.47, 3,238.83 and 861.09

Step by Step Solution

1. Step 1: Write the proportion equation
   2,160.47 : 3,238.83 = 861.09 : x
2. Step 2: Convert to fraction form
   2,160.47/3,238.83 = 861.09/x
3. Step 3: Cross multiply
   2,160.47x = 3,238.83 × 861.09
4. Step 4: Simplify right side
   2,160.47x = 2,788,924.12
5. Step 5: Solve for x
   x = 2,788,924.12/2,160.47
6. Step 6: Final answer
   x = 1,290.89