Finding the Fourth Proportional to 1,139.77, 1,572.89 and 667.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.77 : 1,572.89 = 667.56 : x
2. Step 2: Convert to fraction form
   1,139.77/1,572.89 = 667.56/x
3. Step 3: Cross multiply
   1,139.77x = 1,572.89 × 667.56
4. Step 4: Simplify right side
   1,139.77x = 1,049,987.25
5. Step 5: Solve for x
   x = 1,049,987.25/1,139.77
6. Step 6: Final answer
   x = 921.23