Finding the Fourth Proportional to 1,127.42, 1,689.96 and 639.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,127.42 : 1,689.96 = 639.43 : x
2. Step 2: Convert to fraction form
   1,127.42/1,689.96 = 639.43/x
3. Step 3: Cross multiply
   1,127.42x = 1,689.96 × 639.43
4. Step 4: Simplify right side
   1,127.42x = 1,080,609.30
5. Step 5: Solve for x
   x = 1,080,609.30/1,127.42
6. Step 6: Final answer
   x = 958.48