Finding the Fourth Proportional to 1,271.50, 1,906.56 and 687.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,271.50 : 1,906.56 = 687.20 : x
2. Step 2: Convert to fraction form
   1,271.50/1,906.56 = 687.20/x
3. Step 3: Cross multiply
   1,271.50x = 1,906.56 × 687.20
4. Step 4: Simplify right side
   1,271.50x = 1,310,178.50
5. Step 5: Solve for x
   x = 1,310,178.50/1,271.50
6. Step 6: Final answer
   x = 1,030.42