Finding the Fourth Proportional to 1,039.91, 1,434.45 and 619.98

Step by Step Solution

1. Step 1: Write the proportion equation
   1,039.91 : 1,434.45 = 619.98 : x
2. Step 2: Convert to fraction form
   1,039.91/1,434.45 = 619.98/x
3. Step 3: Cross multiply
   1,039.91x = 1,434.45 × 619.98
4. Step 4: Simplify right side
   1,039.91x = 889,330.80
5. Step 5: Solve for x
   x = 889,330.80/1,039.91
6. Step 6: Final answer
   x = 855.20