Finding the Fourth Proportional to 2,616.87, 3,924.48 and 861.51

Step by Step Solution

1. Step 1: Write the proportion equation
   2,616.87 : 3,924.48 = 861.51 : x
2. Step 2: Convert to fraction form
   2,616.87/3,924.48 = 861.51/x
3. Step 3: Cross multiply
   2,616.87x = 3,924.48 × 861.51
4. Step 4: Simplify right side
   2,616.87x = 3,380,978.76
5. Step 5: Solve for x
   x = 3,380,978.76/2,616.87
6. Step 6: Final answer
   x = 1,291.99