Finding the Fourth Proportional to 1,139.28, 1,572.12 and 641.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.28 : 1,572.12 = 641.82 : x
2. Step 2: Convert to fraction form
   1,139.28/1,572.12 = 641.82/x
3. Step 3: Cross multiply
   1,139.28x = 1,572.12 × 641.82
4. Step 4: Simplify right side
   1,139.28x = 1,009,018.06
5. Step 5: Solve for x
   x = 1,009,018.06/1,139.28
6. Step 6: Final answer
   x = 885.66