Finding the Fourth Proportional to 1,039.90, 1,558.50 and 422.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,039.90 : 1,558.50 = 422.89 : x
2. Step 2: Convert to fraction form
   1,039.90/1,558.50 = 422.89/x
3. Step 3: Cross multiply
   1,039.90x = 1,558.50 × 422.89
4. Step 4: Simplify right side
   1,039.90x = 659,064.16
5. Step 5: Solve for x
   x = 659,064.16/1,039.90
6. Step 6: Final answer
   x = 633.78