Finding the Fourth Proportional to 1,422.07, 1,961.88 and 861.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,422.07 : 1,961.88 = 861.57 : x
2. Step 2: Convert to fraction form
   1,422.07/1,961.88 = 861.57/x
3. Step 3: Cross multiply
   1,422.07x = 1,961.88 × 861.57
4. Step 4: Simplify right side
   1,422.07x = 1,690,292.91
5. Step 5: Solve for x
   x = 1,690,292.91/1,422.07
6. Step 6: Final answer
   x = 1,188.61