Finding the Third Proportional to 139.78 and 304.31

Step by Step Solution

1. Step 1: Write the proportion equation
   139.78 : 304.31 = 304.31 : x
2. Step 2: Convert to fraction form
   139.78/304.31 = 304.31/x
3. Step 3: Cross multiply
   139.78x = 304.31 × 304.31
4. Step 4: Simplify right side
   139.78x = 92,606.10
5. Step 5: Solve for x
   x = 92,606.10/139.78
6. Step 6: Final answer
   x = 662.51