Finding the Fourth Proportional to 1,392.67, 1,921.35 and 869.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,392.67 : 1,921.35 = 869.05 : x
2. Step 2: Convert to fraction form
   1,392.67/1,921.35 = 869.05/x
3. Step 3: Cross multiply
   1,392.67x = 1,921.35 × 869.05
4. Step 4: Simplify right side
   1,392.67x = 1,669,749.22
5. Step 5: Solve for x
   x = 1,669,749.22/1,392.67
6. Step 6: Final answer
   x = 1,198.96