Finding the Fourth Proportional to 1,187.56, 1,638.55 and 715.33

Step by Step Solution

1. Step 1: Write the proportion equation
   1,187.56 : 1,638.55 = 715.33 : x
2. Step 2: Convert to fraction form
   1,187.56/1,638.55 = 715.33/x
3. Step 3: Cross multiply
   1,187.56x = 1,638.55 × 715.33
4. Step 4: Simplify right side
   1,187.56x = 1,172,100.77
5. Step 5: Solve for x
   x = 1,172,100.77/1,187.56
6. Step 6: Final answer
   x = 986.98