Finding the Fourth Proportional to 1,420.56, 1,959.78 and 861.06

Step by Step Solution

1. Step 1: Write the proportion equation
   1,420.56 : 1,959.78 = 861.06 : x
2. Step 2: Convert to fraction form
   1,420.56/1,959.78 = 861.06/x
3. Step 3: Cross multiply
   1,420.56x = 1,959.78 × 861.06
4. Step 4: Simplify right side
   1,420.56x = 1,687,488.17
5. Step 5: Solve for x
   x = 1,687,488.17/1,420.56
6. Step 6: Final answer
   x = 1,187.90