Finding the Fourth Proportional to 1,187.88, 1,638.81 and 690.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,187.88 : 1,638.81 = 690.43 : x
2. Step 2: Convert to fraction form
   1,187.88/1,638.81 = 690.43/x
3. Step 3: Cross multiply
   1,187.88x = 1,638.81 × 690.43
4. Step 4: Simplify right side
   1,187.88x = 1,131,483.59
5. Step 5: Solve for x
   x = 1,131,483.59/1,187.88
6. Step 6: Final answer
   x = 952.52