Finding the Fourth Proportional to 1,013.95, 1,399.55 and 620.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,013.95 : 1,399.55 = 620.89 : x
2. Step 2: Convert to fraction form
   1,013.95/1,399.55 = 620.89/x
3. Step 3: Cross multiply
   1,013.95x = 1,399.55 × 620.89
4. Step 4: Simplify right side
   1,013.95x = 868,956.50
5. Step 5: Solve for x
   x = 868,956.50/1,013.95
6. Step 6: Final answer
   x = 857.01