Finding the Fourth Proportional to 1,139.32, 1,572.14 and 641.95

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.32 : 1,572.14 = 641.95 : x
2. Step 2: Convert to fraction form
   1,139.32/1,572.14 = 641.95/x
3. Step 3: Cross multiply
   1,139.32x = 1,572.14 × 641.95
4. Step 4: Simplify right side
   1,139.32x = 1,009,235.27
5. Step 5: Solve for x
   x = 1,009,235.27/1,139.32
6. Step 6: Final answer
   x = 885.82