Finding the Fourth Proportional to 1,392.42, 1,921.86 and 861.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,392.42 : 1,921.86 = 861.42 : x
2. Step 2: Convert to fraction form
   1,392.42/1,921.86 = 861.42/x
3. Step 3: Cross multiply
   1,392.42x = 1,921.86 × 861.42
4. Step 4: Simplify right side
   1,392.42x = 1,655,528.64
5. Step 5: Solve for x
   x = 1,655,528.64/1,392.42
6. Step 6: Final answer
   x = 1,188.96