Finding the Third Proportional to 123.50 and 251.50

Step by Step Solution

1. Step 1: Write the proportion equation
   123.50 : 251.50 = 251.50 : x
2. Step 2: Convert to fraction form
   123.50/251.50 = 251.50/x
3. Step 3: Cross multiply
   123.50x = 251.50 × 251.50
4. Step 4: Simplify right side
   123.50x = 63,252.25
5. Step 5: Solve for x
   x = 63,252.25/123.50
6. Step 6: Final answer
   x = 512.16