Finding the Fourth Proportional to 1,039.57, 1,434.91 and 620.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,039.57 : 1,434.91 = 620.21 : x
2. Step 2: Convert to fraction form
   1,039.57/1,434.91 = 620.21/x
3. Step 3: Cross multiply
   1,039.57x = 1,434.91 × 620.21
4. Step 4: Simplify right side
   1,039.57x = 889,945.53
5. Step 5: Solve for x
   x = 889,945.53/1,039.57
6. Step 6: Final answer
   x = 856.07