Finding the Third Proportional to 99.98 and 211.78

Step by Step Solution

1. Step 1: Write the proportion equation
   99.98 : 211.78 = 211.78 : x
2. Step 2: Convert to fraction form
   99.98/211.78 = 211.78/x
3. Step 3: Cross multiply
   99.98x = 211.78 × 211.78
4. Step 4: Simplify right side
   99.98x = 44,851.30
5. Step 5: Solve for x
   x = 44,851.30/99.98
6. Step 6: Final answer
   x = 448.58