Finding the Third Proportional to 99,878 and 213,972

Step by Step Solution

1. Step 1: Write the proportion equation
   99,878 : 213,972 = 213,972 : x
2. Step 2: Convert to fraction form
   99,878/213,972 = 213,972/x
3. Step 3: Cross multiply
   99,878x = 213,972 × 213,972
4. Step 4: Simplify right side
   99,878x = 45,784,016,784
5. Step 5: Solve for x
   x = 45,784,016,784/99,878
6. Step 6: Final answer
   x = 458,399.42