Finding the Fourth Proportional to 1,187.31, 1,638.50 and 690.26

Step by Step Solution

1. Step 1: Write the proportion equation
   1,187.31 : 1,638.50 = 690.26 : x
2. Step 2: Convert to fraction form
   1,187.31/1,638.50 = 690.26/x
3. Step 3: Cross multiply
   1,187.31x = 1,638.50 × 690.26
4. Step 4: Simplify right side
   1,187.31x = 1,130,979.37
5. Step 5: Solve for x
   x = 1,130,979.37/1,187.31
6. Step 6: Final answer
   x = 952.56