Finding the Third Proportional to 86.91 and 136.69

Step by Step Solution

1. Step 1: Write the proportion equation
   86.91 : 136.69 = 136.69 : x
2. Step 2: Convert to fraction form
   86.91/136.69 = 136.69/x
3. Step 3: Cross multiply
   86.91x = 136.69 × 136.69
4. Step 4: Simplify right side
   86.91x = 18,683.47
5. Step 5: Solve for x
   x = 18,683.47/86.91
6. Step 6: Final answer
   x = 214.98