Finding the Third Proportional to 80 and 111.50

Step by Step Solution

1. Step 1: Write the proportion equation
   80 : 111.50 = 111.50 : x
2. Step 2: Convert to fraction form
   80/111.50 = 111.50/x
3. Step 3: Cross multiply
   80x = 111.50 × 111.50
4. Step 4: Simplify right side
   80x = 12,432.25
5. Step 5: Solve for x
   x = 12,432.25/80
6. Step 6: Final answer
   x = 155.40