Finding the Third Proportional to 42.50 and 76.88

Step by Step Solution

1. Step 1: Write the proportion equation
   42.50 : 76.88 = 76.88 : x
2. Step 2: Convert to fraction form
   42.50/76.88 = 76.88/x
3. Step 3: Cross multiply
   42.50x = 76.88 × 76.88
4. Step 4: Simplify right side
   42.50x = 5,909.77
5. Step 5: Solve for x
   x = 5,909.77/42.50
6. Step 6: Final answer
   x = 139.05