Finding the Fourth Proportional to 1,012.31, 1,397.02 and 619.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,012.31 : 1,397.02 = 619.55 : x
2. Step 2: Convert to fraction form
   1,012.31/1,397.02 = 619.55/x
3. Step 3: Cross multiply
   1,012.31x = 1,397.02 × 619.55
4. Step 4: Simplify right side
   1,012.31x = 865,523.74
5. Step 5: Solve for x
   x = 865,523.74/1,012.31
6. Step 6: Final answer
   x = 855.00