Finding the Fourth Proportional to 1,293.60, 1,938.72 and 861.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,293.60 : 1,938.72 = 861.12 : x
2. Step 2: Convert to fraction form
   1,293.60/1,938.72 = 861.12/x
3. Step 3: Cross multiply
   1,293.60x = 1,938.72 × 861.12
4. Step 4: Simplify right side
   1,293.60x = 1,669,470.57
5. Step 5: Solve for x
   x = 1,669,470.57/1,293.60
6. Step 6: Final answer
   x = 1,290.56