Finding the Third Proportional to 259.45 and 402.15

Step by Step Solution

1. Step 1: Write the proportion equation
   259.45 : 402.15 = 402.15 : x
2. Step 2: Convert to fraction form
   259.45/402.15 = 402.15/x
3. Step 3: Cross multiply
   259.45x = 402.15 × 402.15
4. Step 4: Simplify right side
   259.45x = 161,726.51
5. Step 5: Solve for x
   x = 161,726.51/259.45
6. Step 6: Final answer
   x = 623.34