Finding the Fourth Proportional to 1,003.50, 1,505.55 and 426.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,003.50 : 1,505.55 = 426.42 : x
2. Step 2: Convert to fraction form
   1,003.50/1,505.55 = 426.42/x
3. Step 3: Cross multiply
   1,003.50x = 1,505.55 × 426.42
4. Step 4: Simplify right side
   1,003.50x = 641,996.63
5. Step 5: Solve for x
   x = 641,996.63/1,003.50
6. Step 6: Final answer
   x = 639.76