Finding the Third Proportional to 99,978 and 212,685

Step by Step Solution

1. Step 1: Write the proportion equation
   99,978 : 212,685 = 212,685 : x
2. Step 2: Convert to fraction form
   99,978/212,685 = 212,685/x
3. Step 3: Cross multiply
   99,978x = 212,685 × 212,685
4. Step 4: Simplify right side
   99,978x = 45,234,909,225
5. Step 5: Solve for x
   x = 45,234,909,225/99,978
6. Step 6: Final answer
   x = 452,448.63