Finding the Fourth Proportional to 1,139.56, 1,572.45 and 667.11

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.56 : 1,572.45 = 667.11 : x
2. Step 2: Convert to fraction form
   1,139.56/1,572.45 = 667.11/x
3. Step 3: Cross multiply
   1,139.56x = 1,572.45 × 667.11
4. Step 4: Simplify right side
   1,139.56x = 1,048,990.93
5. Step 5: Solve for x
   x = 1,048,990.93/1,139.56
6. Step 6: Final answer
   x = 920.52