Finding the Third Proportional to 640,978 and 978,417

Step by Step Solution

1. Step 1: Write the proportion equation
   640,978 : 978,417 = 978,417 : x
2. Step 2: Convert to fraction form
   640,978/978,417 = 978,417/x
3. Step 3: Cross multiply
   640,978x = 978,417 × 978,417
4. Step 4: Simplify right side
   640,978x = 957,299,825,889
5. Step 5: Solve for x
   x = 957,299,825,889/640,978
6. Step 6: Final answer
   x = 1,493,498.73