Finding the Third Proportional to 67.78 and 139.22

Step by Step Solution

1. Step 1: Write the proportion equation
   67.78 : 139.22 = 139.22 : x
2. Step 2: Convert to fraction form
   67.78/139.22 = 139.22/x
3. Step 3: Cross multiply
   67.78x = 139.22 × 139.22
4. Step 4: Simplify right side
   67.78x = 19,381.86
5. Step 5: Solve for x
   x = 19,381.86/67.78
6. Step 6: Final answer
   x = 285.95