Finding the Fourth Proportional to 1,114.55, 1,538.15 and 642.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,114.55 : 1,538.15 = 642.57 : x
2. Step 2: Convert to fraction form
   1,114.55/1,538.15 = 642.57/x
3. Step 3: Cross multiply
   1,114.55x = 1,538.15 × 642.57
4. Step 4: Simplify right side
   1,114.55x = 988,360.06
5. Step 5: Solve for x
   x = 988,360.06/1,114.55
6. Step 6: Final answer
   x = 886.78