Finding the Fourth Proportional to 1,008.72, 1,391.40 and 615.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,008.72 : 1,391.40 = 615.42 : x
2. Step 2: Convert to fraction form
   1,008.72/1,391.40 = 615.42/x
3. Step 3: Cross multiply
   1,008.72x = 1,391.40 × 615.42
4. Step 4: Simplify right side
   1,008.72x = 856,295.39
5. Step 5: Solve for x
   x = 856,295.39/1,008.72
6. Step 6: Final answer
   x = 848.89