Finding the Third Proportional to 99,978 and 216,912

Step by Step Solution

1. Step 1: Write the proportion equation
   99,978 : 216,912 = 216,912 : x
2. Step 2: Convert to fraction form
   99,978/216,912 = 216,912/x
3. Step 3: Cross multiply
   99,978x = 216,912 × 216,912
4. Step 4: Simplify right side
   99,978x = 47,050,815,744
5. Step 5: Solve for x
   x = 47,050,815,744/99,978
6. Step 6: Final answer
   x = 470,611.69