Finding the Fourth Proportional to 1,139.67, 1,572.72 and 667.51

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.67 : 1,572.72 = 667.51 : x
2. Step 2: Convert to fraction form
   1,139.67/1,572.72 = 667.51/x
3. Step 3: Cross multiply
   1,139.67x = 1,572.72 × 667.51
4. Step 4: Simplify right side
   1,139.67x = 1,049,806.33
5. Step 5: Solve for x
   x = 1,049,806.33/1,139.67
6. Step 6: Final answer
   x = 921.15