Finding the Fourth Proportional to 1,131.70, 1,697.60 and 638.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,131.70 : 1,697.60 = 638.10 : x
2. Step 2: Convert to fraction form
   1,131.70/1,697.60 = 638.10/x
3. Step 3: Cross multiply
   1,131.70x = 1,697.60 × 638.10
4. Step 4: Simplify right side
   1,131.70x = 1,083,238.56
5. Step 5: Solve for x
   x = 1,083,238.56/1,131.70
6. Step 6: Final answer
   x = 957.18