Finding the Third Proportional to 258,691.50 and 386,443.50

Step by Step Solution

1. Step 1: Write the proportion equation
   258,691.50 : 386,443.50 = 386,443.50 : x
2. Step 2: Convert to fraction form
   258,691.50/386,443.50 = 386,443.50/x
3. Step 3: Cross multiply
   258,691.50x = 386,443.50 × 386,443.50
4. Step 4: Simplify right side
   258,691.50x = 149,338,578,692.25
5. Step 5: Solve for x
   x = 149,338,578,692.25/258,691.50
6. Step 6: Final answer
   x = 577,284.44