Finding the Fourth Proportional to 1,187.51, 1,638.50 and 689.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,187.51 : 1,638.50 = 689.89 : x
2. Step 2: Convert to fraction form
   1,187.51/1,638.50 = 689.89/x
3. Step 3: Cross multiply
   1,187.51x = 1,638.50 × 689.89
4. Step 4: Simplify right side
   1,187.51x = 1,130,379.81
5. Step 5: Solve for x
   x = 1,130,379.81/1,187.51
6. Step 6: Final answer
   x = 951.89