Finding the Fourth Proportional to 1,187.81, 1,638.88 and 892.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,187.81 : 1,638.88 = 892.57 : x
2. Step 2: Convert to fraction form
   1,187.81/1,638.88 = 892.57/x
3. Step 3: Cross multiply
   1,187.81x = 1,638.88 × 892.57
4. Step 4: Simplify right side
   1,187.81x = 1,462,816.89
5. Step 5: Solve for x
   x = 1,462,816.89/1,187.81
6. Step 6: Final answer
   x = 1,231.52