Finding the Third Proportional to 389,868.50 and 620,290

Step by Step Solution

1. Step 1: Write the proportion equation
   389,868.50 : 620,290 = 620,290 : x
2. Step 2: Convert to fraction form
   389,868.50/620,290 = 620,290/x
3. Step 3: Cross multiply
   389,868.50x = 620,290 × 620,290
4. Step 4: Simplify right side
   389,868.50x = 384,759,684,100
5. Step 5: Solve for x
   x = 384,759,684,100/389,868.50
6. Step 6: Final answer
   x = 986,896.05