Finding the Third Proportional to 309,215.50 and 665,178

Step by Step Solution

1. Step 1: Write the proportion equation
   309,215.50 : 665,178 = 665,178 : x
2. Step 2: Convert to fraction form
   309,215.50/665,178 = 665,178/x
3. Step 3: Cross multiply
   309,215.50x = 665,178 × 665,178
4. Step 4: Simplify right side
   309,215.50x = 442,461,771,684
5. Step 5: Solve for x
   x = 442,461,771,684/309,215.50
6. Step 6: Final answer
   x = 1,430,917.18