Finding the Third Proportional to 139.25 and 290.50

Step by Step Solution

1. Step 1: Write the proportion equation
   139.25 : 290.50 = 290.50 : x
2. Step 2: Convert to fraction form
   139.25/290.50 = 290.50/x
3. Step 3: Cross multiply
   139.25x = 290.50 × 290.50
4. Step 4: Simplify right side
   139.25x = 84,390.25
5. Step 5: Solve for x
   x = 84,390.25/139.25
6. Step 6: Final answer
   x = 606.03