Finding the Fourth Proportional to 1,011.61, 1,517.69 and 426.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,011.61 : 1,517.69 = 426.31 : x
2. Step 2: Convert to fraction form
   1,011.61/1,517.69 = 426.31/x
3. Step 3: Cross multiply
   1,011.61x = 1,517.69 × 426.31
4. Step 4: Simplify right side
   1,011.61x = 647,006.42
5. Step 5: Solve for x
   x = 647,006.42/1,011.61
6. Step 6: Final answer
   x = 639.58