Finding the Fourth Proportional to 1,392.53, 1,921.12 and 861.03

Step by Step Solution

1. Step 1: Write the proportion equation
   1,392.53 : 1,921.12 = 861.03 : x
2. Step 2: Convert to fraction form
   1,392.53/1,921.12 = 861.03/x
3. Step 3: Cross multiply
   1,392.53x = 1,921.12 × 861.03
4. Step 4: Simplify right side
   1,392.53x = 1,654,139.80
5. Step 5: Solve for x
   x = 1,654,139.80/1,392.53
6. Step 6: Final answer
   x = 1,187.87