Finding the Fourth Proportional to 1,187.49, 1,638.78 and 715.37

Step by Step Solution

1. Step 1: Write the proportion equation
   1,187.49 : 1,638.78 = 715.37 : x
2. Step 2: Convert to fraction form
   1,187.49/1,638.78 = 715.37/x
3. Step 3: Cross multiply
   1,187.49x = 1,638.78 × 715.37
4. Step 4: Simplify right side
   1,187.49x = 1,172,325.85
5. Step 5: Solve for x
   x = 1,172,325.85/1,187.49
6. Step 6: Final answer
   x = 987.23