Finding the Third Proportional to 257,998.50 and 398,500

Step by Step Solution

1. Step 1: Write the proportion equation
   257,998.50 : 398,500 = 398,500 : x
2. Step 2: Convert to fraction form
   257,998.50/398,500 = 398,500/x
3. Step 3: Cross multiply
   257,998.50x = 398,500 × 398,500
4. Step 4: Simplify right side
   257,998.50x = 158,802,250,000
5. Step 5: Solve for x
   x = 158,802,250,000/257,998.50
6. Step 6: Final answer
   x = 615,516.18