Finding the Third Proportional to 42.78 and 87.72

Step by Step Solution

1. Step 1: Write the proportion equation
   42.78 : 87.72 = 87.72 : x
2. Step 2: Convert to fraction form
   42.78/87.72 = 87.72/x
3. Step 3: Cross multiply
   42.78x = 87.72 × 87.72
4. Step 4: Simplify right side
   42.78x = 7,694.58
5. Step 5: Solve for x
   x = 7,694.58/42.78
6. Step 6: Final answer
   x = 179.86