Finding the Third Proportional to 123.40 and 207.56

Step by Step Solution

1. Step 1: Write the proportion equation
   123.40 : 207.56 = 207.56 : x
2. Step 2: Convert to fraction form
   123.40/207.56 = 207.56/x
3. Step 3: Cross multiply
   123.40x = 207.56 × 207.56
4. Step 4: Simplify right side
   123.40x = 43,082.19
5. Step 5: Solve for x
   x = 43,082.19/123.40
6. Step 6: Final answer
   x = 349.13