Finding the Third Proportional to 257,985 and 398,479.50

Step by Step Solution

1. Step 1: Write the proportion equation
   257,985 : 398,479.50 = 398,479.50 : x
2. Step 2: Convert to fraction form
   257,985/398,479.50 = 398,479.50/x
3. Step 3: Cross multiply
   257,985x = 398,479.50 × 398,479.50
4. Step 4: Simplify right side
   257,985x = 158,785,911,920.25
5. Step 5: Solve for x
   x = 158,785,911,920.25/257,985
6. Step 6: Final answer
   x = 615,485.06