Finding the Fourth Proportional to 1,013.18, 1,398.89 and 620.47

Step by Step Solution

1. Step 1: Write the proportion equation
   1,013.18 : 1,398.89 = 620.47 : x
2. Step 2: Convert to fraction form
   1,013.18/1,398.89 = 620.47/x
3. Step 3: Cross multiply
   1,013.18x = 1,398.89 × 620.47
4. Step 4: Simplify right side
   1,013.18x = 867,969.28
5. Step 5: Solve for x
   x = 867,969.28/1,013.18
6. Step 6: Final answer
   x = 856.68