Finding the Third Proportional to 61 and 89

Step by Step Solution

1. Step 1: Write the proportion equation
   61 : 89 = 89 : x
2. Step 2: Convert to fraction form
   61/89 = 89/x
3. Step 3: Cross multiply
   61x = 89 × 89
4. Step 4: Simplify right side
   61x = 7,921
5. Step 5: Solve for x
   x = 7,921/61
6. Step 6: Final answer
   x = 129.85