Finding the Fourth Proportional to 1,187.38, 1,638.52 and 663.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,187.38 : 1,638.52 = 663.31 : x
2. Step 2: Convert to fraction form
   1,187.38/1,638.52 = 663.31/x
3. Step 3: Cross multiply
   1,187.38x = 1,638.52 × 663.31
4. Step 4: Simplify right side
   1,187.38x = 1,086,846.70
5. Step 5: Solve for x
   x = 1,086,846.70/1,187.38
6. Step 6: Final answer
   x = 915.33