Finding the Third Proportional to 259.31 and 401.51

Step by Step Solution

1. Step 1: Write the proportion equation
   259.31 : 401.51 = 401.51 : x
2. Step 2: Convert to fraction form
   259.31/401.51 = 401.51/x
3. Step 3: Cross multiply
   259.31x = 401.51 × 401.51
4. Step 4: Simplify right side
   259.31x = 161,208.52
5. Step 5: Solve for x
   x = 161,208.52/259.31
6. Step 6: Final answer
   x = 621.68