Finding the Fourth Proportional to 1,139.16, 1,572.09 and 641.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.16 : 1,572.09 = 641.82 : x
2. Step 2: Convert to fraction form
   1,139.16/1,572.09 = 641.82/x
3. Step 3: Cross multiply
   1,139.16x = 1,572.09 × 641.82
4. Step 4: Simplify right side
   1,139.16x = 1,009,005.90
5. Step 5: Solve for x
   x = 1,009,005.90/1,139.16
6. Step 6: Final answer
   x = 885.74