Finding the Fourth Proportional to 2,505.60, 3,758.70 and 861.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,505.60 : 3,758.70 = 861.72 : x
2. Step 2: Convert to fraction form
   2,505.60/3,758.70 = 861.72/x
3. Step 3: Cross multiply
   2,505.60x = 3,758.70 × 861.72
4. Step 4: Simplify right side
   2,505.60x = 3,238,946.96
5. Step 5: Solve for x
   x = 3,238,946.96/2,505.60
6. Step 6: Final answer
   x = 1,292.68