Finding the Fourth Proportional to 1,047.65, 1,571.42 and 431.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,047.65 : 1,571.42 = 431.34 : x
2. Step 2: Convert to fraction form
   1,047.65/1,571.42 = 431.34/x
3. Step 3: Cross multiply
   1,047.65x = 1,571.42 × 431.34
4. Step 4: Simplify right side
   1,047.65x = 677,814.15
5. Step 5: Solve for x
   x = 677,814.15/1,047.65
6. Step 6: Final answer
   x = 646.99