Finding the Fourth Proportional to 1,420.86, 1,960.73 and 861.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,420.86 : 1,960.73 = 861.56 : x
2. Step 2: Convert to fraction form
   1,420.86/1,960.73 = 861.56/x
3. Step 3: Cross multiply
   1,420.86x = 1,960.73 × 861.56
4. Step 4: Simplify right side
   1,420.86x = 1,689,272.43
5. Step 5: Solve for x
   x = 1,689,272.43/1,420.86
6. Step 6: Final answer
   x = 1,188.91