Finding the Third Proportional to 61.31 and 138.38

Step by Step Solution

1. Step 1: Write the proportion equation
   61.31 : 138.38 = 138.38 : x
2. Step 2: Convert to fraction form
   61.31/138.38 = 138.38/x
3. Step 3: Cross multiply
   61.31x = 138.38 × 138.38
4. Step 4: Simplify right side
   61.31x = 19,147.64
5. Step 5: Solve for x
   x = 19,147.64/61.31
6. Step 6: Final answer
   x = 312.30