Finding the Fourth Proportional to 1,187.58, 1,638.81 and 690.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,187.58 : 1,638.81 = 690.18 : x
2. Step 2: Convert to fraction form
   1,187.58/1,638.81 = 690.18/x
3. Step 3: Cross multiply
   1,187.58x = 1,638.81 × 690.18
4. Step 4: Simplify right side
   1,187.58x = 1,131,073.89
5. Step 5: Solve for x
   x = 1,131,073.89/1,187.58
6. Step 6: Final answer
   x = 952.42