Finding the Third Proportional to 291,865.50 and 639,090

Step by Step Solution

1. Step 1: Write the proportion equation
   291,865.50 : 639,090 = 639,090 : x
2. Step 2: Convert to fraction form
   291,865.50/639,090 = 639,090/x
3. Step 3: Cross multiply
   291,865.50x = 639,090 × 639,090
4. Step 4: Simplify right side
   291,865.50x = 408,436,028,100
5. Step 5: Solve for x
   x = 408,436,028,100/291,865.50
6. Step 6: Final answer
   x = 1,399,398.11