Finding the Third Proportional to 621.50 and 1,109

Step by Step Solution

1. Step 1: Write the proportion equation
   621.50 : 1,109 = 1,109 : x
2. Step 2: Convert to fraction form
   621.50/1,109 = 1,109/x
3. Step 3: Cross multiply
   621.50x = 1,109 × 1,109
4. Step 4: Simplify right side
   621.50x = 1,229,881
5. Step 5: Solve for x
   x = 1,229,881/621.50
6. Step 6: Final answer
   x = 1,978.89