Finding the Third Proportional to 99,910 and 213,990

Step by Step Solution

1. Step 1: Write the proportion equation
   99,910 : 213,990 = 213,990 : x
2. Step 2: Convert to fraction form
   99,910/213,990 = 213,990/x
3. Step 3: Cross multiply
   99,910x = 213,990 × 213,990
4. Step 4: Simplify right side
   99,910x = 45,791,720,100
5. Step 5: Solve for x
   x = 45,791,720,100/99,910
6. Step 6: Final answer
   x = 458,329.70