Finding the Third Proportional to 259.45 and 388.55

Step by Step Solution

1. Step 1: Write the proportion equation
   259.45 : 388.55 = 388.55 : x
2. Step 2: Convert to fraction form
   259.45/388.55 = 388.55/x
3. Step 3: Cross multiply
   259.45x = 388.55 × 388.55
4. Step 4: Simplify right side
   259.45x = 150,968.67
5. Step 5: Solve for x
   x = 150,968.67/259.45
6. Step 6: Final answer
   x = 581.87