Finding the Third Proportional to 76.78 and 154.69

Step by Step Solution

1. Step 1: Write the proportion equation
   76.78 : 154.69 = 154.69 : x
2. Step 2: Convert to fraction form
   76.78/154.69 = 154.69/x
3. Step 3: Cross multiply
   76.78x = 154.69 × 154.69
4. Step 4: Simplify right side
   76.78x = 23,928.22
5. Step 5: Solve for x
   x = 23,928.22/76.78
6. Step 6: Final answer
   x = 311.64