Finding the Fourth Proportional to 1,139.69, 1,572.77 and 615.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.69 : 1,572.77 = 615.72 : x
2. Step 2: Convert to fraction form
   1,139.69/1,572.77 = 615.72/x
3. Step 3: Cross multiply
   1,139.69x = 1,572.77 × 615.72
4. Step 4: Simplify right side
   1,139.69x = 968,385.94
5. Step 5: Solve for x
   x = 968,385.94/1,139.69
6. Step 6: Final answer
   x = 849.69