Finding the Third Proportional to 78.56 and 138.56

Step by Step Solution

1. Step 1: Write the proportion equation
   78.56 : 138.56 = 138.56 : x
2. Step 2: Convert to fraction form
   78.56/138.56 = 138.56/x
3. Step 3: Cross multiply
   78.56x = 138.56 × 138.56
4. Step 4: Simplify right side
   78.56x = 19,199.57
5. Step 5: Solve for x
   x = 19,199.57/78.56
6. Step 6: Final answer
   x = 244.39