Finding the Fourth Proportional to 1,187.33, 1,638.59 and 663.35

Step by Step Solution

1. Step 1: Write the proportion equation
   1,187.33 : 1,638.59 = 663.35 : x
2. Step 2: Convert to fraction form
   1,187.33/1,638.59 = 663.35/x
3. Step 3: Cross multiply
   1,187.33x = 1,638.59 × 663.35
4. Step 4: Simplify right side
   1,187.33x = 1,086,947.17
5. Step 5: Solve for x
   x = 1,086,947.17/1,187.33
6. Step 6: Final answer
   x = 915.46