Finding the Fourth Proportional to 1,139.12, 1,571.96 and 667.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.12 : 1,571.96 = 667.34 : x
2. Step 2: Convert to fraction form
   1,139.12/1,571.96 = 667.34/x
3. Step 3: Cross multiply
   1,139.12x = 1,571.96 × 667.34
4. Step 4: Simplify right side
   1,139.12x = 1,049,031.79
5. Step 5: Solve for x
   x = 1,049,031.79/1,139.12
6. Step 6: Final answer
   x = 920.91