Finding the Third Proportional to 91.78 and 142.31

Step by Step Solution

1. Step 1: Write the proportion equation
   91.78 : 142.31 = 142.31 : x
2. Step 2: Convert to fraction form
   91.78/142.31 = 142.31/x
3. Step 3: Cross multiply
   91.78x = 142.31 × 142.31
4. Step 4: Simplify right side
   91.78x = 20,252.85
5. Step 5: Solve for x
   x = 20,252.85/91.78
6. Step 6: Final answer
   x = 220.66