Finding the Third Proportional to 99,820 and 218,780

Step by Step Solution

1. Step 1: Write the proportion equation
   99,820 : 218,780 = 218,780 : x
2. Step 2: Convert to fraction form
   99,820/218,780 = 218,780/x
3. Step 3: Cross multiply
   99,820x = 218,780 × 218,780
4. Step 4: Simplify right side
   99,820x = 47,864,688,400
5. Step 5: Solve for x
   x = 47,864,688,400/99,820
6. Step 6: Final answer
   x = 479,510.00