Finding the Fourth Proportional to 1,013.39, 1,398.71 and 620.74

Step by Step Solution

1. Step 1: Write the proportion equation
   1,013.39 : 1,398.71 = 620.74 : x
2. Step 2: Convert to fraction form
   1,013.39/1,398.71 = 620.74/x
3. Step 3: Cross multiply
   1,013.39x = 1,398.71 × 620.74
4. Step 4: Simplify right side
   1,013.39x = 868,225.15
5. Step 5: Solve for x
   x = 868,225.15/1,013.39
6. Step 6: Final answer
   x = 856.76