Finding the Fourth Proportional to 1,139.93, 1,572.99 and 642.52

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.93 : 1,572.99 = 642.52 : x
2. Step 2: Convert to fraction form
   1,139.93/1,572.99 = 642.52/x
3. Step 3: Cross multiply
   1,139.93x = 1,572.99 × 642.52
4. Step 4: Simplify right side
   1,139.93x = 1,010,677.53
5. Step 5: Solve for x
   x = 1,010,677.53/1,139.93
6. Step 6: Final answer
   x = 886.61