Finding the Third Proportional to 111.50 and 243

Step by Step Solution

1. Step 1: Write the proportion equation
   111.50 : 243 = 243 : x
2. Step 2: Convert to fraction form
   111.50/243 = 243/x
3. Step 3: Cross multiply
   111.50x = 243 × 243
4. Step 4: Simplify right side
   111.50x = 59,049
5. Step 5: Solve for x
   x = 59,049/111.50
6. Step 6: Final answer
   x = 529.59