Finding the Third Proportional to 99,980 and 217,456

Step by Step Solution

1. Step 1: Write the proportion equation
   99,980 : 217,456 = 217,456 : x
2. Step 2: Convert to fraction form
   99,980/217,456 = 217,456/x
3. Step 3: Cross multiply
   99,980x = 217,456 × 217,456
4. Step 4: Simplify right side
   99,980x = 47,287,111,936
5. Step 5: Solve for x
   x = 47,287,111,936/99,980
6. Step 6: Final answer
   x = 472,965.71