Finding the Fourth Proportional to 1,421.61, 1,961.82 and 861.93

Step by Step Solution

1. Step 1: Write the proportion equation
   1,421.61 : 1,961.82 = 861.93 : x
2. Step 2: Convert to fraction form
   1,421.61/1,961.82 = 861.93/x
3. Step 3: Cross multiply
   1,421.61x = 1,961.82 × 861.93
4. Step 4: Simplify right side
   1,421.61x = 1,690,951.51
5. Step 5: Solve for x
   x = 1,690,951.51/1,421.61
6. Step 6: Final answer
   x = 1,189.47