Finding the Fourth Proportional to 2,421.45, 3,631.86 and 861.39

Step by Step Solution

1. Step 1: Write the proportion equation
   2,421.45 : 3,631.86 = 861.39 : x
2. Step 2: Convert to fraction form
   2,421.45/3,631.86 = 861.39/x
3. Step 3: Cross multiply
   2,421.45x = 3,631.86 × 861.39
4. Step 4: Simplify right side
   2,421.45x = 3,128,447.89
5. Step 5: Solve for x
   x = 3,128,447.89/2,421.45
6. Step 6: Final answer
   x = 1,291.97