Finding the Third Proportional to 643,410 and 978,939

Step by Step Solution

1. Step 1: Write the proportion equation
   643,410 : 978,939 = 978,939 : x
2. Step 2: Convert to fraction form
   643,410/978,939 = 978,939/x
3. Step 3: Cross multiply
   643,410x = 978,939 × 978,939
4. Step 4: Simplify right side
   643,410x = 958,321,565,721
5. Step 5: Solve for x
   x = 958,321,565,721/643,410
6. Step 6: Final answer
   x = 1,489,441.52