Finding the Fourth Proportional to 1,139.23, 1,572.24 and 641.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.23 : 1,572.24 = 641.89 : x
2. Step 2: Convert to fraction form
   1,139.23/1,572.24 = 641.89/x
3. Step 3: Cross multiply
   1,139.23x = 1,572.24 × 641.89
4. Step 4: Simplify right side
   1,139.23x = 1,009,209.51
5. Step 5: Solve for x
   x = 1,009,209.51/1,139.23
6. Step 6: Final answer
   x = 885.87